Volume 45,Issue 6,2016 Table of Contents
2016, 45(6):1369-1373.
Abstract:
Magnetic properties of conventional grain-oriented electrical steel sheets are different in various directions, Epstein standard samples were cut with different angles to rolling direction and the corresponding magnetic properties of samples were tested. Experimental results shows that the hard magnetization direction is around 60°to the rolling direction. Conventional elliptical models are not accurate to simulate permeability at all magnetic intensities, and parabolic and hybrid models with high accuracy were proposed to simulate relations between permeability and magnetization direction. When magnetic intensity is no less than 10000 A/m, hybrid model could be used, and when magnetic intensity is less than 10000 A/m, parabolic model should be applied. Two-stage relation model of permeability and magnetization angles is significant in improving the accuracy of electromagnetic engineering calculations of electrical steel and could be applied in industrial applications.
Magnetic properties of conventional grain-oriented electrical steel sheets are different in various directions, Epstein standard samples were cut with different angles to rolling direction and the corresponding magnetic properties of samples were tested. Experimental results shows that the hard magnetization direction is around 60°to the rolling direction. Conventional elliptical models are not accurate to simulate permeability at all magnetic intensities, and parabolic and hybrid models with high accuracy were proposed to simulate relations between permeability and magnetization direction. When magnetic intensity is no less than 10000 A/m, hybrid model could be used, and when magnetic intensity is less than 10000 A/m, parabolic model should be applied. Two-stage relation model of permeability and magnetization angles is significant in improving the accuracy of electromagnetic engineering calculations of electrical steel and could be applied in industrial applications.
2016, 45(6):1374-1380.
Abstract:
VO2(B) was synthesized via a facile hydrothermal process using V2O5 and oxalic acid. The crystal structure and phase transition of VO2(B) during elevated temperatures in N2 were investigated by in situ X-ray diffraction (XRD). Meanwhile, the morphology and crystal structure of the samples obtained by annealing at different temperatures were characterized by Field Emission Scanning Electron Microscopy (FE-SEM) and XRD, respectively. The results show the as-synthesized nano platelet-like monoclinic VO2(B) irreversibly transforms into submicron and micron subsphaeroidal tetragonal VO2(R) between 430 and 700 oC. The as-obtained VO2(R) starts to decompose and form Magn閘i phases VnO2n?1 series compounds at 1000 oC, and totally transfers into a corundum V2O3 sintered block at ca. 1200 oC.
VO2(B) was synthesized via a facile hydrothermal process using V2O5 and oxalic acid. The crystal structure and phase transition of VO2(B) during elevated temperatures in N2 were investigated by in situ X-ray diffraction (XRD). Meanwhile, the morphology and crystal structure of the samples obtained by annealing at different temperatures were characterized by Field Emission Scanning Electron Microscopy (FE-SEM) and XRD, respectively. The results show the as-synthesized nano platelet-like monoclinic VO2(B) irreversibly transforms into submicron and micron subsphaeroidal tetragonal VO2(R) between 430 and 700 oC. The as-obtained VO2(R) starts to decompose and form Magn閘i phases VnO2n?1 series compounds at 1000 oC, and totally transfers into a corundum V2O3 sintered block at ca. 1200 oC.
2016, 45(6):1381-1385.
Abstract:
Diborides, including zirconium diboride (ZrB2) and titanium diboride (TiB2), have a number of desirable ceramic qualities that make suitable for preparing ceramic-matrix composites. However, synthesizing a composite based on these materials frequently requires high temperatures and complex synthetic methods. In this study, a nanocrystalline ZrB2-TiB2 powder was synthesized via mechanical alloying (MA) of mixture of elemental Zr, Ti, and B powders mixed at a Zr/Ti/B mole ratio of 1:1:4, a 10:1 ball-to-powder weight ratio, and 500 rpm rotational speed in a planetary ball-mill under argon atmosphere using a ZrO2 vial and balls. MA has the benefits of low-cost, simplicity and high throughputs. The effect of milling time on the phase change was investigated by X-ray diffraction (XRD), and the microstructure development of the powder mixture was monitored by field emission scanning electron microscopy (FESEM) and transmission electron mi-croscopy (TEM). It was found that after 120 h of milling, a nanoscale composite powder with a ~20 nm mean particle size was obtained. Moreover, the TEM examination clearly showed the composite formed between the nanoscale TiB2 and ZrB2 particles. Finally, the milling mechanism was discussed, illustrating the time needed to initiate the reaction and when the fine, homogenous final composite was produced.
Diborides, including zirconium diboride (ZrB2) and titanium diboride (TiB2), have a number of desirable ceramic qualities that make suitable for preparing ceramic-matrix composites. However, synthesizing a composite based on these materials frequently requires high temperatures and complex synthetic methods. In this study, a nanocrystalline ZrB2-TiB2 powder was synthesized via mechanical alloying (MA) of mixture of elemental Zr, Ti, and B powders mixed at a Zr/Ti/B mole ratio of 1:1:4, a 10:1 ball-to-powder weight ratio, and 500 rpm rotational speed in a planetary ball-mill under argon atmosphere using a ZrO2 vial and balls. MA has the benefits of low-cost, simplicity and high throughputs. The effect of milling time on the phase change was investigated by X-ray diffraction (XRD), and the microstructure development of the powder mixture was monitored by field emission scanning electron microscopy (FESEM) and transmission electron mi-croscopy (TEM). It was found that after 120 h of milling, a nanoscale composite powder with a ~20 nm mean particle size was obtained. Moreover, the TEM examination clearly showed the composite formed between the nanoscale TiB2 and ZrB2 particles. Finally, the milling mechanism was discussed, illustrating the time needed to initiate the reaction and when the fine, homogenous final composite was produced.
2016, 45(6):1386-1390.
Abstract:
In this work, the agglomerated ZrB2-MoSi2 composite powders were successfully prepared by spray drying and sintering. The spray-dried ZrB2-30wt.%MoSi2 (SZM) composite coating was manufactured by low pressure plasma spray (LPPS) using the agglomerated powders. For comparison, the mechanically-mixed ZrB2-30wt.%MoSi2 (MZM) composite coating was also prepared by LPPS. The composite powders and coatings were characterized by X-ray diffraction and scanning electron microscopy. The mobility and loose density of the agglomerated powders were measured by hall flowmeter and loose density instrument, respectively. Microhardness, porosity and oxidation behavior of the coatings also were investigated. The results show that, when the spray-dried powders were sintered at 1200℃ for 1 h, The mobility and loose density were up to 25.8 s/50g and 1.12 g/cm3, respectively. The MoSi2 phase of SZM coating distributed much more uniformly than that of MZM coating. Additionally, the SZM coating had high compactness and much better oxidation-resistance at 1500℃ compared to the MZM coating.
In this work, the agglomerated ZrB2-MoSi2 composite powders were successfully prepared by spray drying and sintering. The spray-dried ZrB2-30wt.%MoSi2 (SZM) composite coating was manufactured by low pressure plasma spray (LPPS) using the agglomerated powders. For comparison, the mechanically-mixed ZrB2-30wt.%MoSi2 (MZM) composite coating was also prepared by LPPS. The composite powders and coatings were characterized by X-ray diffraction and scanning electron microscopy. The mobility and loose density of the agglomerated powders were measured by hall flowmeter and loose density instrument, respectively. Microhardness, porosity and oxidation behavior of the coatings also were investigated. The results show that, when the spray-dried powders were sintered at 1200℃ for 1 h, The mobility and loose density were up to 25.8 s/50g and 1.12 g/cm3, respectively. The MoSi2 phase of SZM coating distributed much more uniformly than that of MZM coating. Additionally, the SZM coating had high compactness and much better oxidation-resistance at 1500℃ compared to the MZM coating.
2016, 45(6):1391-1395.
Abstract:
High yield orthorhombic single-crystalline KNbO3 nanowires with widths of 60-150 nm and lengths up to a few microns were synthesized with a template-directed process in a hydrothermal reaction. For the first time, Nb2O5 nanobelts were used as reactants as well as templates in the hydrothermal process. The phase of products was determined by XRD, and the morphology and structure were characterized by SEM, TEM, HRTEM, SAED techniques. The growth direction of KNbO3 was determined to be the [001] crystallographic direction. Synthesized nanowires exhibited a second harmonic generation response, an efficient nanoscale second harmonic light source. The excellent nonlinear optical properties of KNbO3 have potential applications in nano-optical devices.
High yield orthorhombic single-crystalline KNbO3 nanowires with widths of 60-150 nm and lengths up to a few microns were synthesized with a template-directed process in a hydrothermal reaction. For the first time, Nb2O5 nanobelts were used as reactants as well as templates in the hydrothermal process. The phase of products was determined by XRD, and the morphology and structure were characterized by SEM, TEM, HRTEM, SAED techniques. The growth direction of KNbO3 was determined to be the [001] crystallographic direction. Synthesized nanowires exhibited a second harmonic generation response, an efficient nanoscale second harmonic light source. The excellent nonlinear optical properties of KNbO3 have potential applications in nano-optical devices.
2016, 45(6):1396-1400.
Abstract:
Submicro-porous nickel wafers were prepared by a molding-decomposition-sintering method, using nickel oxalate nano-rods which were synthesized via a liquid phase precipitation process as precursors, keeping the decomposition temperature of 360?C for 10 minutes, and sintering temperature of 420, 450，480 and 510℃ for 10 minutes respectively, in a tubular oven filled with Ar gas. The study of Infrared spectroscopy (IR) indicated that the precursor as-prepared was pure nickel oxalate. The studies of X-Ray Diffractions (XRD) indicated that the grey wafers as-treated were nickel, which has face-centered cubic crystal structure. The images of Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) showed that the morphology of metal nickel wafers were obvious porous structure. The structure of holes was irregular with 100-1000 nm in diameters, and the hole walls were fiber-like nickel with 100-300 nm in diameters.
Submicro-porous nickel wafers were prepared by a molding-decomposition-sintering method, using nickel oxalate nano-rods which were synthesized via a liquid phase precipitation process as precursors, keeping the decomposition temperature of 360?C for 10 minutes, and sintering temperature of 420, 450，480 and 510℃ for 10 minutes respectively, in a tubular oven filled with Ar gas. The study of Infrared spectroscopy (IR) indicated that the precursor as-prepared was pure nickel oxalate. The studies of X-Ray Diffractions (XRD) indicated that the grey wafers as-treated were nickel, which has face-centered cubic crystal structure. The images of Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) showed that the morphology of metal nickel wafers were obvious porous structure. The structure of holes was irregular with 100-1000 nm in diameters, and the hole walls were fiber-like nickel with 100-300 nm in diameters.
2016, 45(6):1401-1405.
Abstract:
Ultrasonic effects on microstructure evolution and mechanical properties of AZ80 alloy were investigated. The results indicated that with the application of ultrasonic melt treatment, the primary α-Mg phases were transformed from coarse dendrites to nearly fine equiaxed grains, and the β-Mg17Al12 phases at α-Mg boundaries were refined and modified into discontinuous. Besides, the tensile properties of AZ80 alloy were apparently improved after ultrasonic melt treatment, in which the 0.2% tensile yield strength, ultimate tensile strength and elongation were improved from 87MPa, 118MPa and 2.1% to 107MPa, 170MPa and 5.4%, respectively.
Ultrasonic effects on microstructure evolution and mechanical properties of AZ80 alloy were investigated. The results indicated that with the application of ultrasonic melt treatment, the primary α-Mg phases were transformed from coarse dendrites to nearly fine equiaxed grains, and the β-Mg17Al12 phases at α-Mg boundaries were refined and modified into discontinuous. Besides, the tensile properties of AZ80 alloy were apparently improved after ultrasonic melt treatment, in which the 0.2% tensile yield strength, ultimate tensile strength and elongation were improved from 87MPa, 118MPa and 2.1% to 107MPa, 170MPa and 5.4%, respectively.
2016, 45(6):1406-1412.
Abstract:
The formability during semi-solid deformation of Ti-Cu alloys and its mechanical properties after semi-solid forging are investigated. The formability is evaluated by upsetting and die forging tests. Tensile test is also performed to study the mechanical properties of Ti-Cu alloy after semi-solid forging. The results show that low upsetting force can be obtained in the semi-solid state ranging from 1000 °C to 1150°C, which is better than by conventional processing. Die forging tests show excellent workability with a forging ratio of 75% at the temperatures ranging from 1000 °C to 1050°C. The Ti2Cu phase increases with the increase of Cu concentration, and more liquid precipitates during semi-solid deformation at higher temperatures and Cu concentrations, which relaxes the stress concentration caused by solid deformation and improves the formability. Tensile test reveals that semi-solid forged Ti-Cu alloy exhibits higher strength and lower ductility than conventional forged alloy. The Ti-Cu alloy has lower ductility and higher strength with the increasing of Cu concentration. The difference in tensile properties is attributed to the varieties of Ti2Cu precipitates at different Cu concentration and semi-solid forging temperature.
The formability during semi-solid deformation of Ti-Cu alloys and its mechanical properties after semi-solid forging are investigated. The formability is evaluated by upsetting and die forging tests. Tensile test is also performed to study the mechanical properties of Ti-Cu alloy after semi-solid forging. The results show that low upsetting force can be obtained in the semi-solid state ranging from 1000 °C to 1150°C, which is better than by conventional processing. Die forging tests show excellent workability with a forging ratio of 75% at the temperatures ranging from 1000 °C to 1050°C. The Ti2Cu phase increases with the increase of Cu concentration, and more liquid precipitates during semi-solid deformation at higher temperatures and Cu concentrations, which relaxes the stress concentration caused by solid deformation and improves the formability. Tensile test reveals that semi-solid forged Ti-Cu alloy exhibits higher strength and lower ductility than conventional forged alloy. The Ti-Cu alloy has lower ductility and higher strength with the increasing of Cu concentration. The difference in tensile properties is attributed to the varieties of Ti2Cu precipitates at different Cu concentration and semi-solid forging temperature.
2016, 45(6):1413-1418.
Abstract:
Ti-Ni shape memory alloys with and without Y were aluminized at 650℃ using pack-cementation method. The influence of various amounts of Y addition on the microstructure and isothermal oxidation behaviors of aluminide coatings in air at 700℃ was investigated. The aluminide coatings exhibited double layer structure even the aluminization progress is mainly controlled by inward diffusion of Al. Addition of Y promotes the growth of outer TiAl3 layer, but retards the growth of inner NiAl3 layer when Y is below 1at. %. Isothermal oxidation result indicated that the addition of 0.5 at. %Y significantly reduced scale growth rate. In contrast, 1at. %Y and 5at. % Y addition significantly increased the oxidation rate, especially the latter. The effect of Y on the coating formation and the coating oxidation behavior was discussed in details.
Ti-Ni shape memory alloys with and without Y were aluminized at 650℃ using pack-cementation method. The influence of various amounts of Y addition on the microstructure and isothermal oxidation behaviors of aluminide coatings in air at 700℃ was investigated. The aluminide coatings exhibited double layer structure even the aluminization progress is mainly controlled by inward diffusion of Al. Addition of Y promotes the growth of outer TiAl3 layer, but retards the growth of inner NiAl3 layer when Y is below 1at. %. Isothermal oxidation result indicated that the addition of 0.5 at. %Y significantly reduced scale growth rate. In contrast, 1at. %Y and 5at. % Y addition significantly increased the oxidation rate, especially the latter. The effect of Y on the coating formation and the coating oxidation behavior was discussed in details.
2016, 45(6):1419-1422.
Abstract:
In this study, Nd-doped ZnO thin film has been prepared by electrodeposition method. The structural and optical properties of the samples were investigated. X-ray diffraction spectroscopy analyses indicate that the Nd doping can not disturb the structure of ZnO. No additional peaks are observed in the samples and Nd3 substitute for Zn2 without changing the wurtzite structure. The optical absorption spectra of Nd-doped ZnO thin films indicate that with Nd doping concentration increases, the absorbance peaks of the samples shift towards short wave length. The photoluminescence spectra show that with the concentration of Nd3 increasing, visible emission enhanced greatly and the intensity of ultraviolet emission is reduced.
In this study, Nd-doped ZnO thin film has been prepared by electrodeposition method. The structural and optical properties of the samples were investigated. X-ray diffraction spectroscopy analyses indicate that the Nd doping can not disturb the structure of ZnO. No additional peaks are observed in the samples and Nd3 substitute for Zn2 without changing the wurtzite structure. The optical absorption spectra of Nd-doped ZnO thin films indicate that with Nd doping concentration increases, the absorbance peaks of the samples shift towards short wave length. The photoluminescence spectra show that with the concentration of Nd3 increasing, visible emission enhanced greatly and the intensity of ultraviolet emission is reduced.
2016, 45(6):1423-1429.
Abstract:
In the present work, the microstructure evolution of a novel Al-Cu-Li alloy with rare earth cerium (Ce) additions (0, 0.1, 0.3, and 0.5 wt.%) were investigated. The as-cast samples were characterized by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and electron probe microanalysis (EPMA) with wavelength dispersive spectroscopic (WDS). The microstructural observation showed that the grains were significantly refined with increasing the addition contents of rare earth Ce. A Mg Ag-rich Al7Cu4Li intermetallic phase was observed in all experimental alloys except for the alloy with addition of 0.5wt.? that may be attributed to emerged an extra gray CuSi(AgMg) phase. Furthermore, the coarse rodlike Al2CuLi phase was completely absent with Ce level up to 0.3wt.%. The analysis shows that the Ce addition introduces changes in the precipitation sequence and consequently in the solidification behavior of the alloy. It can be deduced that the grain refinement is mainly the result of the primary Al8Cu4Ce promoting a (Al) nucleation and further prohibiting the grain growth for the cerium addition experimental alloys.
In the present work, the microstructure evolution of a novel Al-Cu-Li alloy with rare earth cerium (Ce) additions (0, 0.1, 0.3, and 0.5 wt.%) were investigated. The as-cast samples were characterized by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and electron probe microanalysis (EPMA) with wavelength dispersive spectroscopic (WDS). The microstructural observation showed that the grains were significantly refined with increasing the addition contents of rare earth Ce. A Mg Ag-rich Al7Cu4Li intermetallic phase was observed in all experimental alloys except for the alloy with addition of 0.5wt.? that may be attributed to emerged an extra gray CuSi(AgMg) phase. Furthermore, the coarse rodlike Al2CuLi phase was completely absent with Ce level up to 0.3wt.%. The analysis shows that the Ce addition introduces changes in the precipitation sequence and consequently in the solidification behavior of the alloy. It can be deduced that the grain refinement is mainly the result of the primary Al8Cu4Ce promoting a (Al) nucleation and further prohibiting the grain growth for the cerium addition experimental alloys.
2016, 45(6):1430-1436.
Abstract:
Mg2B2O5w/6061Al matrix composites were fabricated through the powder metallurgy (PM) technique. The relationship among the parameters of ball milling, the powder characteristics, and the mechanical properties of hot extruded composites was investigated. The results showed that the reinforcement whisker accelerated the milling process by increasing the matrix deformation and enhancing the welding and the fracture of particles. And the mixing process was modified by using a higher milling speed, and suitable milling time, which resulted in the reduction of crystal size, improved homogeneity of the whisker distribution, as well as the enhanced tensile strengths of the hot extruded composites.
Mg2B2O5w/6061Al matrix composites were fabricated through the powder metallurgy (PM) technique. The relationship among the parameters of ball milling, the powder characteristics, and the mechanical properties of hot extruded composites was investigated. The results showed that the reinforcement whisker accelerated the milling process by increasing the matrix deformation and enhancing the welding and the fracture of particles. And the mixing process was modified by using a higher milling speed, and suitable milling time, which resulted in the reduction of crystal size, improved homogeneity of the whisker distribution, as well as the enhanced tensile strengths of the hot extruded composites.
2016, 45(6):1437-1442.
Abstract:
Abstract:Directionally solidified Rene88DT superalloy ingots were successfully produced by electroslag remelting continuous directional solidification (ESR-CDS) technology. Compared with conventional ESR ingot, the as-cast structures of ESR-CDS Rene88DT alloy ingot were analyzed using by optical microscopy (OM)、field emission scanning electron microscopy (FESEM) with energy spectrum and transmission electron microscopy(TEM). The results showed that the ESR-CDS Rene88DT alloy ingot eliminated the region of the severe central segregation which existed commonly in the conventional ESR ingot because of the formation of intersection of interfaces between columnar crystal and equiaxed crystal or columnar crystal each other. In addition, the ESR-CDS Rene88DT alloy ingot showed smaller secondary dendritic spacing, smaller non-equilibrium precipitates phase. Due to the decreasing micro-segregation level, uniform distribution of alloy elements can be achieved when subjected to the heat treatment at 1200 oC for 24h. Statistical results of inclusions revealed that the maximum size of inclusion in the ESR-CDS Rene88DT alloy was not more than 5.89μm and the inclusion volume reduced by 60% compared with conventional ESR and P/M respectively. The hot working plasticity of directionally solidified Rene88DT superalloy can be improved, which makes a basis for implementation of cast-and-wrought (C&W) route.
Abstract:Directionally solidified Rene88DT superalloy ingots were successfully produced by electroslag remelting continuous directional solidification (ESR-CDS) technology. Compared with conventional ESR ingot, the as-cast structures of ESR-CDS Rene88DT alloy ingot were analyzed using by optical microscopy (OM)、field emission scanning electron microscopy (FESEM) with energy spectrum and transmission electron microscopy(TEM). The results showed that the ESR-CDS Rene88DT alloy ingot eliminated the region of the severe central segregation which existed commonly in the conventional ESR ingot because of the formation of intersection of interfaces between columnar crystal and equiaxed crystal or columnar crystal each other. In addition, the ESR-CDS Rene88DT alloy ingot showed smaller secondary dendritic spacing, smaller non-equilibrium precipitates phase. Due to the decreasing micro-segregation level, uniform distribution of alloy elements can be achieved when subjected to the heat treatment at 1200 oC for 24h. Statistical results of inclusions revealed that the maximum size of inclusion in the ESR-CDS Rene88DT alloy was not more than 5.89μm and the inclusion volume reduced by 60% compared with conventional ESR and P/M respectively. The hot working plasticity of directionally solidified Rene88DT superalloy can be improved, which makes a basis for implementation of cast-and-wrought (C&W) route.
2016, 45(6):1443-1448.
Abstract:
Abstract：In this paper, Microstructure and mechanical performance of Nb-Ti-Ni alloy membranes for hydrogen permeation were investigated. XRD and SEM were employed to characterize the phases and structure of Nb-Ti-Ni alloys, mechanical property of the alloy membrane were measured in Three-point bending tests. The results indicate that as-melt alloy is mainly two-phase structure, consisting of the primary bcc-Nb (Ni,Ti) solid solution phase, (bcc-Nb（Ni, Ti） β2-NiTi) eutectic phase，the first one acts as functional cell for hydrogen permeation, the last one is structural cell to keep the stability of alloy membrane, and good anti-bending properties have been obtained in these samples with net-shape structural region consisting of eutectic phase. Mechanical properties of Nb-Ti-Ni alloy membranes have been inordinately improved by magnetic heat-treatment (MHT) along the three directions (0? 45?and 90?. An obvious improvement have been observed in the case of N7 sample MHT at both of 0?and 45?angle, and the case of N5 sample MHT at 90?angle. MHT can lead to the change of grain sizes and grain orientations, when MHT at 0?angle, tiny bar-like region (consisting of eutectic phase) were formed and spread along the direction of membrane surface, while some oral-like (or spot-like) region were regularly arranged on the surface, and the region extend vertical to the surface in the case of MHT at 90?angle. It is suggested that suitable MHT is good for the improvement of mechanical property of Nb-Ti-Ni alloy membranes.
Abstract：In this paper, Microstructure and mechanical performance of Nb-Ti-Ni alloy membranes for hydrogen permeation were investigated. XRD and SEM were employed to characterize the phases and structure of Nb-Ti-Ni alloys, mechanical property of the alloy membrane were measured in Three-point bending tests. The results indicate that as-melt alloy is mainly two-phase structure, consisting of the primary bcc-Nb (Ni,Ti) solid solution phase, (bcc-Nb（Ni, Ti） β2-NiTi) eutectic phase，the first one acts as functional cell for hydrogen permeation, the last one is structural cell to keep the stability of alloy membrane, and good anti-bending properties have been obtained in these samples with net-shape structural region consisting of eutectic phase. Mechanical properties of Nb-Ti-Ni alloy membranes have been inordinately improved by magnetic heat-treatment (MHT) along the three directions (0? 45?and 90?. An obvious improvement have been observed in the case of N7 sample MHT at both of 0?and 45?angle, and the case of N5 sample MHT at 90?angle. MHT can lead to the change of grain sizes and grain orientations, when MHT at 0?angle, tiny bar-like region (consisting of eutectic phase) were formed and spread along the direction of membrane surface, while some oral-like (or spot-like) region were regularly arranged on the surface, and the region extend vertical to the surface in the case of MHT at 90?angle. It is suggested that suitable MHT is good for the improvement of mechanical property of Nb-Ti-Ni alloy membranes.
2016, 45(6):1449-1454.
Abstract:
0.7BiFeO3-0.3PbTiO3（BFPT7030）thin films were deposited on LaNiO3/SiO2/Si substrate by sol-gel process. The thin films were annealed in air, O2 flow, air flow and N2 flow in air environment by rapid thermal annealing technique. Films annealed in air, O2 flow and air flow were fully crystallized and showed highly (100) preferred orientation. BFPT7030 thin film annealed in N2 flow could not obtain hysteresis loops because of the bad crystallization. The BFPT7030 thin films annealed in air showed largest Pr with 30μC cm-2 and lowest leakage current density, while film annealed in air flow showed lowest Pr with 13μC cm-2 and largest leakage current. XPS results demonstrate that the Fe3 :Fe2 is 2.09:1, 1.65:1 and 1.5:1 for films annealed in air, O2 flow and air flow, respectively, and the Bi and Pb relative content in the films annealed in O2 flow and air flow is less than that of film annealed in air. Fluctuation of Fe ions valence state and the volatilization of Bi are the main reasons for the generation of oxygen vacancies. Adding O2 gas is helpful to prevent the generation of oxygen vacancies. Although volatilization of Pb would lead to inferior microstructure, but no oxygen vacancies generated during the process of volatilization of Pb.
0.7BiFeO3-0.3PbTiO3（BFPT7030）thin films were deposited on LaNiO3/SiO2/Si substrate by sol-gel process. The thin films were annealed in air, O2 flow, air flow and N2 flow in air environment by rapid thermal annealing technique. Films annealed in air, O2 flow and air flow were fully crystallized and showed highly (100) preferred orientation. BFPT7030 thin film annealed in N2 flow could not obtain hysteresis loops because of the bad crystallization. The BFPT7030 thin films annealed in air showed largest Pr with 30μC cm-2 and lowest leakage current density, while film annealed in air flow showed lowest Pr with 13μC cm-2 and largest leakage current. XPS results demonstrate that the Fe3 :Fe2 is 2.09:1, 1.65:1 and 1.5:1 for films annealed in air, O2 flow and air flow, respectively, and the Bi and Pb relative content in the films annealed in O2 flow and air flow is less than that of film annealed in air. Fluctuation of Fe ions valence state and the volatilization of Bi are the main reasons for the generation of oxygen vacancies. Adding O2 gas is helpful to prevent the generation of oxygen vacancies. Although volatilization of Pb would lead to inferior microstructure, but no oxygen vacancies generated during the process of volatilization of Pb.
2016, 45(6):1455-1460.
Abstract:
Dotted matrix structures on Ti6Al4V surfaces with different spacing were manufactured by laser technology. The low surface energy materials were deposited on above Ti6Al4V substrates by self-assembled technique in order to prepare hydrophobic/superhydrophobic surfaces. The static contact angle and roll angle of all specimens were measured by self designed measuring system. The moving process of drop dripping was recorded by high speed camera system. The results indicate that the hydrophobic/superhydrophobic surfaces can be gained by dotted matrix structure manufacturing and self-assembled technique, and the contact angle decreases with the spacing of dotted matrix increasing. The static contact angle is relevant to the height of drop dripping, and depends on the drop volume and the last dripping height. The spreading coefficient of drop on the horizontal surface is determined by the roughness and static contact angle, the bigger the roughness and static contact angle is, the smaller the spreading coefficient. With the increase of slope angle, the spreading coefficient decreases and the jump distance increases. The movement of drop dripping on slope surfaces is greatly influenced by the dripping height, roll angel and slope angle.
Dotted matrix structures on Ti6Al4V surfaces with different spacing were manufactured by laser technology. The low surface energy materials were deposited on above Ti6Al4V substrates by self-assembled technique in order to prepare hydrophobic/superhydrophobic surfaces. The static contact angle and roll angle of all specimens were measured by self designed measuring system. The moving process of drop dripping was recorded by high speed camera system. The results indicate that the hydrophobic/superhydrophobic surfaces can be gained by dotted matrix structure manufacturing and self-assembled technique, and the contact angle decreases with the spacing of dotted matrix increasing. The static contact angle is relevant to the height of drop dripping, and depends on the drop volume and the last dripping height. The spreading coefficient of drop on the horizontal surface is determined by the roughness and static contact angle, the bigger the roughness and static contact angle is, the smaller the spreading coefficient. With the increase of slope angle, the spreading coefficient decreases and the jump distance increases. The movement of drop dripping on slope surfaces is greatly influenced by the dripping height, roll angel and slope angle.
2016, 45(6):1461-1466.
Abstract:
Base on equal pressure method, isothermal compression tests of AZ31 magnesium alloy at different strain rates of 0.005-5 s?1 and different deformation temperatures of 473-673K were performed by using Gleeble-1500 simulator. The in?uences of deformation temperature and strain rate on the ?ow stress and critical fracture strain were investigated, and established the basic model of critical fracture strain of AZ31. And then the predicted edge cracking model of hot rolling for AZ31 was obtained based on the basic principles of magnesium alloy rolling edge cracking and fracture criterion of Cockcroft Latham, which contains the material deformation activation energy and the technology parameters of rolling. In order to verify the correctness of the predicted edge cracking model was established ,the corresponding relationship was obtained between damage value and edge crack depth along the width direction by the finite element simulation and rolling experiments in the same conditions. The results showed that the average error was 11.3% between predicted values and measured values .
Base on equal pressure method, isothermal compression tests of AZ31 magnesium alloy at different strain rates of 0.005-5 s?1 and different deformation temperatures of 473-673K were performed by using Gleeble-1500 simulator. The in?uences of deformation temperature and strain rate on the ?ow stress and critical fracture strain were investigated, and established the basic model of critical fracture strain of AZ31. And then the predicted edge cracking model of hot rolling for AZ31 was obtained based on the basic principles of magnesium alloy rolling edge cracking and fracture criterion of Cockcroft Latham, which contains the material deformation activation energy and the technology parameters of rolling. In order to verify the correctness of the predicted edge cracking model was established ,the corresponding relationship was obtained between damage value and edge crack depth along the width direction by the finite element simulation and rolling experiments in the same conditions. The results showed that the average error was 11.3% between predicted values and measured values .
2016, 45(6):1467-1472.
Abstract:
Using the characteristics of dual-directional extrusion and sprial deformation, a new extrusion technique of dual-directional extrusion and sprial compound deformation was proposed. Effect of sprial angle and groove radius on the accumulated strain of the deformed billet was analyzed by using DEFORM-3D software, the proper structure parameters were obtained, and the actual die was manufactured for experimental research. The research results show that the dual-directional extrusion and sprial compound deformation can greatly improve the effective strain of magnesium alloy, with the increase of sprial Angle and groove radius, the effective strain value is increased accordingly, however, the degree of strain inhomogeneity grows. Spiral angle of 40 ° and groove radius of 0.8 mm can obtain superior equivalent strain value and uniform equivalent strain distribution, and grain structure is refined dramatically.
Using the characteristics of dual-directional extrusion and sprial deformation, a new extrusion technique of dual-directional extrusion and sprial compound deformation was proposed. Effect of sprial angle and groove radius on the accumulated strain of the deformed billet was analyzed by using DEFORM-3D software, the proper structure parameters were obtained, and the actual die was manufactured for experimental research. The research results show that the dual-directional extrusion and sprial compound deformation can greatly improve the effective strain of magnesium alloy, with the increase of sprial Angle and groove radius, the effective strain value is increased accordingly, however, the degree of strain inhomogeneity grows. Spiral angle of 40 ° and groove radius of 0.8 mm can obtain superior equivalent strain value and uniform equivalent strain distribution, and grain structure is refined dramatically.
2016, 45(6):1473-1476.
Abstract:
Mg-3Y-0.6Zr-X alloys was prepared by mixed gas protection . The microstucture and mechanical properties of the alloys adding Sm、Ce were analyzed by means of optical microscope(OM), X-ray diffraction analysis (XRD), scanning electron nicroscopy (SEM) , and drawing machine . The results show that the addition of Ce and Sm refines the alloy grain and makes structure more uniform . The tensile strength of alloy increased by 48% with the addition of Sm ; The mechanical properties of the alloy is worsen with the composite addition of Sm and Ce . The yield strength is improved markedly after adding Zn .
Mg-3Y-0.6Zr-X alloys was prepared by mixed gas protection . The microstucture and mechanical properties of the alloys adding Sm、Ce were analyzed by means of optical microscope(OM), X-ray diffraction analysis (XRD), scanning electron nicroscopy (SEM) , and drawing machine . The results show that the addition of Ce and Sm refines the alloy grain and makes structure more uniform . The tensile strength of alloy increased by 48% with the addition of Sm ; The mechanical properties of the alloy is worsen with the composite addition of Sm and Ce . The yield strength is improved markedly after adding Zn .
2016, 45(6):1477-1482.
Abstract:
Porous Ti-6Mo alloy was prepared from mixed powders of Ti, Mo and binder by selective laser sintering, and the structural characteristics and mechanical properties were investigated. The results show that the pore features are connected with the sintering process. As the sintering temperature rises from 1000 to 1200 ℃, the pore morphology changes gradually from interconnected to isolated pores, and the porosity level reduces from 58% to 24%, as well as the pore size from 112 to 43 μm. The porous alloy exhibits a laminar microstructure composed of dominant α and minor β phases together with trace amounts of α-Ti precipitations at room temperature. The compressive stress-strain curves consist of elastic deformation, plastic yield and fracture stage. The elastic modulus and yield strength increase respectively in the ranges 2.07-11.9 GPa and 31.4-152.8 MPa with the decrease in porosity, meanwhile the relationship between the relative mechanical properties and relative density is found to obey a power law relation. Porous Ti-6Mo alloy may be a feasible biomaterial based on the fact that both porous structure and mechanical properties can achieve the requirement of natural bones.
Porous Ti-6Mo alloy was prepared from mixed powders of Ti, Mo and binder by selective laser sintering, and the structural characteristics and mechanical properties were investigated. The results show that the pore features are connected with the sintering process. As the sintering temperature rises from 1000 to 1200 ℃, the pore morphology changes gradually from interconnected to isolated pores, and the porosity level reduces from 58% to 24%, as well as the pore size from 112 to 43 μm. The porous alloy exhibits a laminar microstructure composed of dominant α and minor β phases together with trace amounts of α-Ti precipitations at room temperature. The compressive stress-strain curves consist of elastic deformation, plastic yield and fracture stage. The elastic modulus and yield strength increase respectively in the ranges 2.07-11.9 GPa and 31.4-152.8 MPa with the decrease in porosity, meanwhile the relationship between the relative mechanical properties and relative density is found to obey a power law relation. Porous Ti-6Mo alloy may be a feasible biomaterial based on the fact that both porous structure and mechanical properties can achieve the requirement of natural bones.
2016, 45(6):1483-1487.
Abstract:
ABSTRCT: The intermetallic compound Cu3Sn and Cu6Sn5 which generated in lead-free solder Sn3.0Ag0.5Cu were studied and characterised by nanoindentation. The strain-rate is 0.01 s-1, 0.05s-1, 0.25s-1, 0.5s-1 respectively. The strain-rate effect on mechanical properties of Cu3Sn and Cu6Sn5 were studied. The mechanical responses of both Cu6Sn5 and Cu3Sn (IMCs) show large dependence on the strain rate during loading. In addition, multiple pop-in events are observed in Cu6Sn5 but not evident in Cu3Sn. During loading, the contact stiffness of IMCs increases almost linearly with the indentation depth under each strain rate. In total, the hardness and elastic modulus of Cu3Sn are larger than those of Cu6Sn5, and the hardness of both Cu6Sn5 and Cu3Sn increase with increasing strain rate. During the holding stage, creep deformations of IMCs increase as loading strain rate increases. During the holding stage, creep displacement increases with the increasing strain rate during loading. The creep strain rate sensitivity index m of Cu, Cu3Sn , Cu6Sn5 and solder are 0.01627、0.0117、0.0184 and 0.0661 respectively when the strain-rate is 0.05s-1.
ABSTRCT: The intermetallic compound Cu3Sn and Cu6Sn5 which generated in lead-free solder Sn3.0Ag0.5Cu were studied and characterised by nanoindentation. The strain-rate is 0.01 s-1, 0.05s-1, 0.25s-1, 0.5s-1 respectively. The strain-rate effect on mechanical properties of Cu3Sn and Cu6Sn5 were studied. The mechanical responses of both Cu6Sn5 and Cu3Sn (IMCs) show large dependence on the strain rate during loading. In addition, multiple pop-in events are observed in Cu6Sn5 but not evident in Cu3Sn. During loading, the contact stiffness of IMCs increases almost linearly with the indentation depth under each strain rate. In total, the hardness and elastic modulus of Cu3Sn are larger than those of Cu6Sn5, and the hardness of both Cu6Sn5 and Cu3Sn increase with increasing strain rate. During the holding stage, creep deformations of IMCs increase as loading strain rate increases. During the holding stage, creep displacement increases with the increasing strain rate during loading. The creep strain rate sensitivity index m of Cu, Cu3Sn , Cu6Sn5 and solder are 0.01627、0.0117、0.0184 and 0.0661 respectively when the strain-rate is 0.05s-1.
2016, 45(6):1488-1494.
Abstract:
The microstructure and mechanical properties of AZ61-1Sm-xSb alloy were investigated. The results shown that the mainly phase of AZ61-1Sm-xSb alloy were β-Mg17Al12, Al2Sm, Al3Sm and SbSm. Compared with AZ61, the shape of Mg17Al12 in AZ61-1Sm alloy are discontinuous; Due to the addition of Sm and Sb, the microstructure is further refined, and a new SmSb phase is formed. Addition of Sm and Sb enhanced the strength of hot-extruded and T5 AZ61 alloys at room temperature. Moreover adding Sb into AZ61-1Sm alloy could enhance its strength at 150℃ obviously.
The microstructure and mechanical properties of AZ61-1Sm-xSb alloy were investigated. The results shown that the mainly phase of AZ61-1Sm-xSb alloy were β-Mg17Al12, Al2Sm, Al3Sm and SbSm. Compared with AZ61, the shape of Mg17Al12 in AZ61-1Sm alloy are discontinuous; Due to the addition of Sm and Sb, the microstructure is further refined, and a new SmSb phase is formed. Addition of Sm and Sb enhanced the strength of hot-extruded and T5 AZ61 alloys at room temperature. Moreover adding Sb into AZ61-1Sm alloy could enhance its strength at 150℃ obviously.
2016, 45(6):1495-1499.
Abstract:
The microstructure evolution during isothermal compression at different deformation temperatures and strain rates and water quench after β heating of near-α TA15 titanium alloy with initial equiaxed microstructure was investigated using X-ray diffraction (XRD)，electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) analysis．The tensile strength and elongation were measured by conducting micro-tensile property tests．The results show that α phase globularization occurs when the alloy is deformed at α β temperature range．High temperature β phase transforms into martensite α'' after water cooling．The alloy is composed of equiaxed α，lamellar secondary α and acicular martensite α''．When the alloy is compressed at β temperature range，the microstructure is basically acicular martensite α'' phase．At the temperature range below or above phase transformation point，with the increasing of temperature，the tensile strength decreases and the elongation increases．But at the temperature ranges around phase transformation point，with the increasing of temperature，the tensile strength increases and the elongation decreases．At the two-phase region near phase transition point，better strength and plasticity can be obtained．
The microstructure evolution during isothermal compression at different deformation temperatures and strain rates and water quench after β heating of near-α TA15 titanium alloy with initial equiaxed microstructure was investigated using X-ray diffraction (XRD)，electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) analysis．The tensile strength and elongation were measured by conducting micro-tensile property tests．The results show that α phase globularization occurs when the alloy is deformed at α β temperature range．High temperature β phase transforms into martensite α'' after water cooling．The alloy is composed of equiaxed α，lamellar secondary α and acicular martensite α''．When the alloy is compressed at β temperature range，the microstructure is basically acicular martensite α'' phase．At the temperature range below or above phase transformation point，with the increasing of temperature，the tensile strength decreases and the elongation increases．But at the temperature ranges around phase transformation point，with the increasing of temperature，the tensile strength increases and the elongation decreases．At the two-phase region near phase transition point，better strength and plasticity can be obtained．
2016, 45(6):1500-1504.
Abstract:
It is of benefit for synthesizing and reusing process design of LiCoO2 to understand systemically the physicochemical property of LiCoO2 in the different conditions. In this paper, the mixture samples of LiCoO2 and NaHSO4稨2O with the molar ratio of 1:3, LiCoO2 and Na2S2O7 with the molar ratio of 1:1.5 were roasted. Occurrence evolution and distribution of elements in the sulfating roasting process of LiCoO2 have been studied by TG-DSC-MS, XRD, SEM and EDS. The results showed that reactions have been taken place in roasting. Occurrence of Na element is Na2SO4, LiNaSO4 and Na6Co(SO4)4. Occurrence of Li, Co element is LiNaSO4 and Na6Co(SO4)4 respectively in roasting products. The roasting products have a dense tissue and irregular shape. Distribution of Co element is homogeneous in the roasting products.
It is of benefit for synthesizing and reusing process design of LiCoO2 to understand systemically the physicochemical property of LiCoO2 in the different conditions. In this paper, the mixture samples of LiCoO2 and NaHSO4稨2O with the molar ratio of 1:3, LiCoO2 and Na2S2O7 with the molar ratio of 1:1.5 were roasted. Occurrence evolution and distribution of elements in the sulfating roasting process of LiCoO2 have been studied by TG-DSC-MS, XRD, SEM and EDS. The results showed that reactions have been taken place in roasting. Occurrence of Na element is Na2SO4, LiNaSO4 and Na6Co(SO4)4. Occurrence of Li, Co element is LiNaSO4 and Na6Co(SO4)4 respectively in roasting products. The roasting products have a dense tissue and irregular shape. Distribution of Co element is homogeneous in the roasting products.
2016, 45(6):1505-1508.
Abstract:
In situ tungsten particle reinforced Fe-Al-Cr composites were synthesized by laser induced sintering using Fe50-x/2Al50-x/2Crx (x=4, 8, 12, 16) 1wt% pct W powders. The microstructure and properties of the synthesized alloy with various Cr content were studied. By means of the observation of OLYMPUS4000, XRD, hardness test, abrasion test and corrosion resistance, studied the different Cr content for sintered alloy organization and the influence of the properties.The results showed that the sintered alloys were mainly consisted of Fe3Al, Al2O3, AlCrFe2, Cr2O3 and W phases. The needle-like microstructure is fine and good dispersed, while the abrasion rate is the lowest, about 0.38mg?mm-2, when Cr content is 8%. The hardness and correction resistance of the alloy is the best, when the content of Cr is 12%. The value of hardness, corrosion potential and passivation current density is 1145HV, 327.643mV and 1.044mA?cm-2, respectively.
In situ tungsten particle reinforced Fe-Al-Cr composites were synthesized by laser induced sintering using Fe50-x/2Al50-x/2Crx (x=4, 8, 12, 16) 1wt% pct W powders. The microstructure and properties of the synthesized alloy with various Cr content were studied. By means of the observation of OLYMPUS4000, XRD, hardness test, abrasion test and corrosion resistance, studied the different Cr content for sintered alloy organization and the influence of the properties.The results showed that the sintered alloys were mainly consisted of Fe3Al, Al2O3, AlCrFe2, Cr2O3 and W phases. The needle-like microstructure is fine and good dispersed, while the abrasion rate is the lowest, about 0.38mg?mm-2, when Cr content is 8%. The hardness and correction resistance of the alloy is the best, when the content of Cr is 12%. The value of hardness, corrosion potential and passivation current density is 1145HV, 327.643mV and 1.044mA?cm-2, respectively.
2016, 45(6):1509-1514.
Abstract:
In order to study the influence of warm laser peening on the thermal relaxation behavior of Inconel718 superalloy, the LP(20℃) IN718 and WLP(260℃) IN718 are served as the research objects. From the view points of microstructure and residual stress, the relationship between temperature, time and residual stress are explored by experiments. The thermal relaxation behavior of residual stress are analyzed from the perspective of material softening and creep-controlled behavior at elevated temperature. The results show that the WLP(260℃) IN718 superalloy has a better performance in residual stress stability, grain size and dislocation density compared with LP(20℃) IN718; the relaxation amplitude increases with the increase of applied temperature, and the thermal stability and dislocation density of residual stress in LP(20℃)IN718 is better than that in WLP(260℃) IN718; the maximum rate of stress relaxation take place at the initial stage of peening process in all conditions, the LP(20℃) and WLP(260℃) surface residual stress have released 68% and 36.7% respectively after exposed 500min at 700℃. Thermal relaxation behavior can be described by Zener–Wert–Avrami function.
In order to study the influence of warm laser peening on the thermal relaxation behavior of Inconel718 superalloy, the LP(20℃) IN718 and WLP(260℃) IN718 are served as the research objects. From the view points of microstructure and residual stress, the relationship between temperature, time and residual stress are explored by experiments. The thermal relaxation behavior of residual stress are analyzed from the perspective of material softening and creep-controlled behavior at elevated temperature. The results show that the WLP(260℃) IN718 superalloy has a better performance in residual stress stability, grain size and dislocation density compared with LP(20℃) IN718; the relaxation amplitude increases with the increase of applied temperature, and the thermal stability and dislocation density of residual stress in LP(20℃)IN718 is better than that in WLP(260℃) IN718; the maximum rate of stress relaxation take place at the initial stage of peening process in all conditions, the LP(20℃) and WLP(260℃) surface residual stress have released 68% and 36.7% respectively after exposed 500min at 700℃. Thermal relaxation behavior can be described by Zener–Wert–Avrami function.
2016, 45(6):1515-1520.
Abstract:
Ni-Fe based superalloys are expected to be employed as 700℃ ultra-supercritical coal fired power plants because of its excellent high temperature strength, oxidation and corrosion resistance, low cost and high workability. In this paper, thermodynamic calculation software JMatPro and Ni-based database were used to analyze the solidification and equilibrium phase precipitation of a new Ni-Fe based superalloy. The effect of Al, Ti, Cr and C additions on the precipitation behaviors of strengthing phases was calculated. The results showed that the main constitution phases were γ、γ′、MC and M23C6. The precipitated temperature and amount of γ′ increased with the increasing Ti and Al contents. With the increase of Cr content, the solidus and liquidus temperature decreased and the amount of M23C6 increased firstly and then decreased. The additions of C content could reduce the freezing range and promote the amount and precipitated temperature of MC and M23C6. These results are beneficial to the superalloys design and development.
Ni-Fe based superalloys are expected to be employed as 700℃ ultra-supercritical coal fired power plants because of its excellent high temperature strength, oxidation and corrosion resistance, low cost and high workability. In this paper, thermodynamic calculation software JMatPro and Ni-based database were used to analyze the solidification and equilibrium phase precipitation of a new Ni-Fe based superalloy. The effect of Al, Ti, Cr and C additions on the precipitation behaviors of strengthing phases was calculated. The results showed that the main constitution phases were γ、γ′、MC and M23C6. The precipitated temperature and amount of γ′ increased with the increasing Ti and Al contents. With the increase of Cr content, the solidus and liquidus temperature decreased and the amount of M23C6 increased firstly and then decreased. The additions of C content could reduce the freezing range and promote the amount and precipitated temperature of MC and M23C6. These results are beneficial to the superalloys design and development.
2016, 45(6):1521-1525.
Abstract:
Bulk metallic glass formations in Mg-Ni-Y alloy systems are investigated using cluster line approach in combination, and the cluster formulae stability, glass-forming ability (GFA), corrosion resistance properties of sample were investigated by Δ, RDAC, σ, 砢, τ, φ and icorr. The results are shown: Mg32.3Ni21.5Y46.2、Mg30.9Ni40.6Y28.5 and Mg27.2Ni47.8Y25.0 bulk metallic glasses using cluster line criterion have a high Δ, RDAC, σ, 砢, τ, φ, which are advantageous of the cluster formulae stability and the increase of glass-forming ability (GFA). All the sample have a low icorr, which indicate that the Mg-Ni-Y alloys designed show good corrosion resistance in NaOH solution.
Bulk metallic glass formations in Mg-Ni-Y alloy systems are investigated using cluster line approach in combination, and the cluster formulae stability, glass-forming ability (GFA), corrosion resistance properties of sample were investigated by Δ, RDAC, σ, 砢, τ, φ and icorr. The results are shown: Mg32.3Ni21.5Y46.2、Mg30.9Ni40.6Y28.5 and Mg27.2Ni47.8Y25.0 bulk metallic glasses using cluster line criterion have a high Δ, RDAC, σ, 砢, τ, φ, which are advantageous of the cluster formulae stability and the increase of glass-forming ability (GFA). All the sample have a low icorr, which indicate that the Mg-Ni-Y alloys designed show good corrosion resistance in NaOH solution.
2016, 45(6):1526-1530.
Abstract:
In the present work, the mutual effect of Nb and Cu on the microstructure of Zr alloys was investigated. When trace amount of Fe element was presented, the precipitation of Nb and Fe, whose amount was below the equilibrium solid solution limitation in α-Zr, were promoted by the appropriate amount addition of Cu element, leading to the lower content of Nb in α-Zr alloys. However, the precipitation of Nb-enriched phase was inhabited by the further addition of Cu amount since the Fe element was consumed by the enrichment of Zr2Cu phase. Meanwhile, Zr2Cu phase in Zr-1.0Cu alloy was significantly refined and uniformly distributed after the addition of Nb element. In the presence of β-Zr secondary phase stabilized by high amount of Nb element, small amount of Cu element tended to be enriched within the β-Zr phase rather than precipitated as Zr2Cu.
In the present work, the mutual effect of Nb and Cu on the microstructure of Zr alloys was investigated. When trace amount of Fe element was presented, the precipitation of Nb and Fe, whose amount was below the equilibrium solid solution limitation in α-Zr, were promoted by the appropriate amount addition of Cu element, leading to the lower content of Nb in α-Zr alloys. However, the precipitation of Nb-enriched phase was inhabited by the further addition of Cu amount since the Fe element was consumed by the enrichment of Zr2Cu phase. Meanwhile, Zr2Cu phase in Zr-1.0Cu alloy was significantly refined and uniformly distributed after the addition of Nb element. In the presence of β-Zr secondary phase stabilized by high amount of Nb element, small amount of Cu element tended to be enriched within the β-Zr phase rather than precipitated as Zr2Cu.
2016, 45(6):1531-1533.
Abstract:
The kinetics analysis of recrystallizaiton during annealing process of cold-rolled TB8 alloy plate was investigated. The results show that the better annealing temperature of the test material is form 790℃to 810℃. The relationship between annealing time and volume fraction of the recrystallized grains at 800℃ can be described by the Avrami equation of . Based on the kinetics analysis of recrystallization process, the activation energy was calculated to be 102.87KJ/mol.
The kinetics analysis of recrystallizaiton during annealing process of cold-rolled TB8 alloy plate was investigated. The results show that the better annealing temperature of the test material is form 790℃to 810℃. The relationship between annealing time and volume fraction of the recrystallized grains at 800℃ can be described by the Avrami equation of . Based on the kinetics analysis of recrystallization process, the activation energy was calculated to be 102.87KJ/mol.
2016, 45(6):1534-1538.
Abstract:
The tensile strength and fatigue crack propagation rate test were carried out for cold rolled, warm rolled and full annealed Al-6Mg-0.8Zn-0.5Mn-0.2Zr-0.2Er alloy. The microstructure before fatigue test , the fatigue fracture and crack propagation path were observed by using electron back-scattered diffraction(EBSD), transmission electron microscope(TEM) and scanning electron microscope(SEM) in order to analyze the effects of microstructure on tensile property and fatigue crack propagation property. The results show that the fatigue crack propagation rate of warm rolled alloy with high strength is much slower than the cold rolled. The microstructure characterization shows that the warm rolled alloy has more subgrain boundaries than that of the cold rolled and full annealed alloys due to dynamic recovery during warm rolling. This kind of microstructure is conducive to the improvement of yield strength and fatigue crack propagation resistance.
The tensile strength and fatigue crack propagation rate test were carried out for cold rolled, warm rolled and full annealed Al-6Mg-0.8Zn-0.5Mn-0.2Zr-0.2Er alloy. The microstructure before fatigue test , the fatigue fracture and crack propagation path were observed by using electron back-scattered diffraction(EBSD), transmission electron microscope(TEM) and scanning electron microscope(SEM) in order to analyze the effects of microstructure on tensile property and fatigue crack propagation property. The results show that the fatigue crack propagation rate of warm rolled alloy with high strength is much slower than the cold rolled. The microstructure characterization shows that the warm rolled alloy has more subgrain boundaries than that of the cold rolled and full annealed alloys due to dynamic recovery during warm rolling. This kind of microstructure is conducive to the improvement of yield strength and fatigue crack propagation resistance.
2016, 45(6):1539-1544.
Abstract:
The microstructural characteristics of a new-type Fe-Ni-Cr based superalloy was observed by ultra high resolution field emission scanning electron microscopy. The equilibrium precipitated phases and the effects of elements on the melting point and the precipitation behaviors of different phases were calculated by Thermo-Calc software. The results show that a higher C content can lead to higer quantities of MC and M23C6 carbides and higher precipitation temperatures. With the increase of Ti content, the main MC former, there is no obvious change in precipitation amount of MC, but its precipitation temperature range is significantly broadened. With the content of Ti and Al increasing, the precipitation amount and precipitation temperature of γ′ phase can be raised respectively, the effect of Al is particularly remarkable. Lowering Al content or increasing Ti content can dramatically raise the precipitation amount and preciptitation temperatures of η phase. The the formation of MC is not obviously promoted by higher content of W, the MC forming elements. Higer Al, Ti and W content can decrease the initial melting point; especially Al and Ti show more significant effects.
The microstructural characteristics of a new-type Fe-Ni-Cr based superalloy was observed by ultra high resolution field emission scanning electron microscopy. The equilibrium precipitated phases and the effects of elements on the melting point and the precipitation behaviors of different phases were calculated by Thermo-Calc software. The results show that a higher C content can lead to higer quantities of MC and M23C6 carbides and higher precipitation temperatures. With the increase of Ti content, the main MC former, there is no obvious change in precipitation amount of MC, but its precipitation temperature range is significantly broadened. With the content of Ti and Al increasing, the precipitation amount and precipitation temperature of γ′ phase can be raised respectively, the effect of Al is particularly remarkable. Lowering Al content or increasing Ti content can dramatically raise the precipitation amount and preciptitation temperatures of η phase. The the formation of MC is not obviously promoted by higher content of W, the MC forming elements. Higer Al, Ti and W content can decrease the initial melting point; especially Al and Ti show more significant effects.
2016, 45(6):1545-1548.
Abstract:
Ti-5Al-5Mo-5V-1Fe-1Cr Ti alloy is an important aviation material. The microstructure heterogeneity of the alloy during isothermal compression is revealed in this work. The alloy is fabricated via the consumable vacuum arc-remelting furnace. The as-cast ingot is subjected to thermo-mechanical processing and heat treatment. Isothermal compression tests are conducted subsequently. The cylindrical specimens are machined from the heat-treated rods. The two ends of the specimens are not rubbed and polished. The local large deformation zones are observed in the specimens undergoing isothermal compression, which can cause crack nucleation in the material when the material bears load. The microstructural phenomenon is investigated in this work.
Ti-5Al-5Mo-5V-1Fe-1Cr Ti alloy is an important aviation material. The microstructure heterogeneity of the alloy during isothermal compression is revealed in this work. The alloy is fabricated via the consumable vacuum arc-remelting furnace. The as-cast ingot is subjected to thermo-mechanical processing and heat treatment. Isothermal compression tests are conducted subsequently. The cylindrical specimens are machined from the heat-treated rods. The two ends of the specimens are not rubbed and polished. The local large deformation zones are observed in the specimens undergoing isothermal compression, which can cause crack nucleation in the material when the material bears load. The microstructural phenomenon is investigated in this work.
Chen Haisheng
,
Feng Yong
,
Ma Fanjiao
,
Mao Youchuan
,
Liu Xianghong
,
Zhang Pingxiang
,
Kou Hongchao
,
Fu Hengzhi
2016, 45(6):1549-1553.
Abstract:
Elevated-temperature flow behavior of Ti-6Al-3Nb-2Zr-1Mo titanium alloy was investigated by conducting isothermal hot compression tests at strain rate from 0.001 to 1 s-1 and in the temperature range of 820~970 ℃ on Gleeble-3800 simulator. The BP-ANN and regression models were established based on the experimental flow stress. Results show that the absolute value of maximum relative error obtained from the ANN model and regression method were 4.35% and 13.9%, respectively. The average absolute relative errors are 1.42% and 6.53% corresponding to the ANN model and regression method, which demonstrates that BP-ANN has a better prediction precision, and it can be used as the constitutive model of Ti-6Al-3Nb-2Zr-1Mo titanium alloy.
Elevated-temperature flow behavior of Ti-6Al-3Nb-2Zr-1Mo titanium alloy was investigated by conducting isothermal hot compression tests at strain rate from 0.001 to 1 s-1 and in the temperature range of 820~970 ℃ on Gleeble-3800 simulator. The BP-ANN and regression models were established based on the experimental flow stress. Results show that the absolute value of maximum relative error obtained from the ANN model and regression method were 4.35% and 13.9%, respectively. The average absolute relative errors are 1.42% and 6.53% corresponding to the ANN model and regression method, which demonstrates that BP-ANN has a better prediction precision, and it can be used as the constitutive model of Ti-6Al-3Nb-2Zr-1Mo titanium alloy.
2016, 45(6):1554-1558.
Abstract:
The porous Ti-10Mo alloys from elemental powders were fabricated by powder metallurgy technique with ammonium bicarbonate as the space-holder. The effects of sintering process and space-holder content on the microstructure, porous characteristics and mechanical properties were studied. The results show that at sintering temperature of 1300℃ the porous Ti-Mo alloys with uniform microstructure and pore distribution can be produced, and the alloy exhibit a typical Widmanstatten structure. With the increase of the space-holder content, the pores become larger and the hole wall gets thinner. At or above 50wt% of space-holder, pores are interconnected, leading to forming a three-dimensional connectivity structure. When the space-holder content is in the range of 50%~60% , the alloys obtained show porosity of 62.8%~66.9%, and their elastic modulus and compressive yield strength vary from 2.9 to 1.3 GPa, and from 129.2 to 56.1 MPa, respectively.
The porous Ti-10Mo alloys from elemental powders were fabricated by powder metallurgy technique with ammonium bicarbonate as the space-holder. The effects of sintering process and space-holder content on the microstructure, porous characteristics and mechanical properties were studied. The results show that at sintering temperature of 1300℃ the porous Ti-Mo alloys with uniform microstructure and pore distribution can be produced, and the alloy exhibit a typical Widmanstatten structure. With the increase of the space-holder content, the pores become larger and the hole wall gets thinner. At or above 50wt% of space-holder, pores are interconnected, leading to forming a three-dimensional connectivity structure. When the space-holder content is in the range of 50%~60% , the alloys obtained show porosity of 62.8%~66.9%, and their elastic modulus and compressive yield strength vary from 2.9 to 1.3 GPa, and from 129.2 to 56.1 MPa, respectively.
2016, 45(6):1559-1564.
Abstract:
The effects of different amount of Al-5Ti-1B grain refiner on microstructure and secondary solidification of 7A04 aluminum alloy semisolid slurry were investigated. The results show that the primary α-Al particles of 7A04 aluminum alloy semisolid slurry could become fine and globular by addition of 0.1% Al-5Ti-1B grain refiner, the microstructure with average particle diameter 71μm and shape factor 0.49 of primary α-Al particles at 630℃could be obtained.The amount of Al-5Ti-1B grain refiner was higher than 0.1% and the effect of refining was not obvious. As the temperature increased, microstructure of semisolid slurry of 7A04 aluminum alloy got fine but the shape factor deteriorated. The microstructure of semisolid solidification with fine and globular α2 particles could be achieved by addition of Al-5Ti-1B grain refiner, but there was little change with average particle diameter and shape factor of α3 particles.
The effects of different amount of Al-5Ti-1B grain refiner on microstructure and secondary solidification of 7A04 aluminum alloy semisolid slurry were investigated. The results show that the primary α-Al particles of 7A04 aluminum alloy semisolid slurry could become fine and globular by addition of 0.1% Al-5Ti-1B grain refiner, the microstructure with average particle diameter 71μm and shape factor 0.49 of primary α-Al particles at 630℃could be obtained.The amount of Al-5Ti-1B grain refiner was higher than 0.1% and the effect of refining was not obvious. As the temperature increased, microstructure of semisolid slurry of 7A04 aluminum alloy got fine but the shape factor deteriorated. The microstructure of semisolid solidification with fine and globular α2 particles could be achieved by addition of Al-5Ti-1B grain refiner, but there was little change with average particle diameter and shape factor of α3 particles.
2016, 45(6):1565-1570.
Abstract:
The rapid microwave synthesis and sintering of ZrNiSn bulk was studied in this work. The phase composition and microstructure of samples were characterized by using X-ray diffracmeter (XRD) and transmission electron microscope (TEM) technologies. The thermoelectric properties i.e. Seebeck coefficient (S), electrical resistivity (ρ), and thermal conductivity (κ) were measured through Seebeck coefficient/resistance analysis system (S/RAs) and laser flash thermal analyzer (LFT). The analysis results show that a relatively high purity single phase of ZrNiSn alloy was synthesized in merely 4~5min in microwave field, and small amount of impurity of Sn almost eliminated during 30min microwave sintering via secondary reaction. The variation trends of S, ρ and power factor with temperature were analyzed. The electrical resistivity was found has relative high value of 13.7~16.9μΩm. The highest power factor is 1683μWm-1K-2, lower than the previously reported, which should attribute to the high electrical resistivity. The thermal conductivity was decreased with temperature, and its maximum value is 4.288Wm-1K-1. The lattice thermal conductivity is merely 2.86~3.96 Wm-1K-1. The result of microstructure analysis shows that the growth of ZrNiSn grain was inhibited during microwave sintering. A large number of nanometer grains were precipitated in the interior of ZrNiSn grain and on the boundary. The calculated thermoelectric figure of merit (ZT) was found rapid increased with temperature, and a maximum ZT of 0.25 was achieved at 573~673K.
The rapid microwave synthesis and sintering of ZrNiSn bulk was studied in this work. The phase composition and microstructure of samples were characterized by using X-ray diffracmeter (XRD) and transmission electron microscope (TEM) technologies. The thermoelectric properties i.e. Seebeck coefficient (S), electrical resistivity (ρ), and thermal conductivity (κ) were measured through Seebeck coefficient/resistance analysis system (S/RAs) and laser flash thermal analyzer (LFT). The analysis results show that a relatively high purity single phase of ZrNiSn alloy was synthesized in merely 4~5min in microwave field, and small amount of impurity of Sn almost eliminated during 30min microwave sintering via secondary reaction. The variation trends of S, ρ and power factor with temperature were analyzed. The electrical resistivity was found has relative high value of 13.7~16.9μΩm. The highest power factor is 1683μWm-1K-2, lower than the previously reported, which should attribute to the high electrical resistivity. The thermal conductivity was decreased with temperature, and its maximum value is 4.288Wm-1K-1. The lattice thermal conductivity is merely 2.86~3.96 Wm-1K-1. The result of microstructure analysis shows that the growth of ZrNiSn grain was inhibited during microwave sintering. A large number of nanometer grains were precipitated in the interior of ZrNiSn grain and on the boundary. The calculated thermoelectric figure of merit (ZT) was found rapid increased with temperature, and a maximum ZT of 0.25 was achieved at 573~673K.
2016, 45(6):1571-1577.
Abstract:
The microstructures and morphologies of Al/ZE42/Al composite plates were observed by optical microscopy (OM), scanning electron microscopy (SEM). Corrosion rates of the Al/ZE42/Al composite plates at different temperature and holding time were also measured in salt water immersion test, and the influence of annealing on interfacial microstructure of Al/ZE42/Al composite plates and corrosion behaviors in 5.0 wt% NaCl aqueous solution were investigated. The results showed that element diffusion of Mg, Al, Zn, Y and Er in Al/ZE42/Al composite plate interfacial region after annealing was occurred. The interfacial diffusion layer has two reaction layers. Mg17Al12 phase in one reaction layer near ZE42 magnesium alloy, and Al3Mg2 phase in the other reaction layer closed to Al plate. With annealing temperature and holding time increasing, the thickness of ZE42/Al interfacial diffusion layer increased, and at the meanwhile recrystallization behaviors occurred in ZE42 magnesium alloy. Annealing cannot improve corrosion resistance of Al/ZE42/Al composite plate, but improving corrosion rate. The corrosion mechanism of the Al/ZE42/Al composite plate is the aggravation of galvanic corrosion which occurred from edge to internal of the plate.
The microstructures and morphologies of Al/ZE42/Al composite plates were observed by optical microscopy (OM), scanning electron microscopy (SEM). Corrosion rates of the Al/ZE42/Al composite plates at different temperature and holding time were also measured in salt water immersion test, and the influence of annealing on interfacial microstructure of Al/ZE42/Al composite plates and corrosion behaviors in 5.0 wt% NaCl aqueous solution were investigated. The results showed that element diffusion of Mg, Al, Zn, Y and Er in Al/ZE42/Al composite plate interfacial region after annealing was occurred. The interfacial diffusion layer has two reaction layers. Mg17Al12 phase in one reaction layer near ZE42 magnesium alloy, and Al3Mg2 phase in the other reaction layer closed to Al plate. With annealing temperature and holding time increasing, the thickness of ZE42/Al interfacial diffusion layer increased, and at the meanwhile recrystallization behaviors occurred in ZE42 magnesium alloy. Annealing cannot improve corrosion resistance of Al/ZE42/Al composite plate, but improving corrosion rate. The corrosion mechanism of the Al/ZE42/Al composite plate is the aggravation of galvanic corrosion which occurred from edge to internal of the plate.
2016, 45(6):1578-1582.
Abstract:
ZK60 alloy strip was fabricated by Twin Roll Casting (TRC for short) technology in this paper. The effect of heat treatment on microstructure and damping capacities was discussed by using optical microscope (OM) and dynamic mechanical analyzer (DMA). The homogeneous structure was obtained after annealing treatment. The equiaxed recrystallized grains were obtained after T6 treatment. The damping peak P1 is a relaxation process. The activation energy H for P1 was 132KJ/mol. The damping peak P2 is not a relaxation process. It is a recrystallized damping peak. The classical curve of strain amplitude dependence of damping capacity of TRC ZK60 strip was present after T6 treatment (aging for 6hrs), but the curves of strain amplitude dependence of damping capacity of TRC ZK60 strip with two different dislocations system were obtained after the other T6 treatment. Strain amplitude dependence of damping capacity of TRC ZK60 strip after T6 treatment abide by the G-L theory.
ZK60 alloy strip was fabricated by Twin Roll Casting (TRC for short) technology in this paper. The effect of heat treatment on microstructure and damping capacities was discussed by using optical microscope (OM) and dynamic mechanical analyzer (DMA). The homogeneous structure was obtained after annealing treatment. The equiaxed recrystallized grains were obtained after T6 treatment. The damping peak P1 is a relaxation process. The activation energy H for P1 was 132KJ/mol. The damping peak P2 is not a relaxation process. It is a recrystallized damping peak. The classical curve of strain amplitude dependence of damping capacity of TRC ZK60 strip was present after T6 treatment (aging for 6hrs), but the curves of strain amplitude dependence of damping capacity of TRC ZK60 strip with two different dislocations system were obtained after the other T6 treatment. Strain amplitude dependence of damping capacity of TRC ZK60 strip after T6 treatment abide by the G-L theory.
2016, 45(6):1583-1587.
Abstract:
The effect of solution heat treatment on the microstructure and properties of hot-rolled GH3535 superalloyhas been investigated by Scanning Electron Microscope (SEM), Electron Back scattered Diffraction (EBSD) and tensile tests. Significant grain growth and carbide dissolution occur after solution treated at 1177°C for 20min. With the rise of the solution temperature up to 1220°Cand 1260°C, the grain size grows abnormally and the amounts of M6C carbides decrease significantly.Tensile tests indicated that higher solution temperature and longer solution time lead to the decrease of ultimate tensile strength and the improvement of elongation. The grain growth and carbide dissolution are responsible for the evolution of tensile properties in GH3535 superalloy after different solution heat treatments.
The effect of solution heat treatment on the microstructure and properties of hot-rolled GH3535 superalloyhas been investigated by Scanning Electron Microscope (SEM), Electron Back scattered Diffraction (EBSD) and tensile tests. Significant grain growth and carbide dissolution occur after solution treated at 1177°C for 20min. With the rise of the solution temperature up to 1220°Cand 1260°C, the grain size grows abnormally and the amounts of M6C carbides decrease significantly.Tensile tests indicated that higher solution temperature and longer solution time lead to the decrease of ultimate tensile strength and the improvement of elongation. The grain growth and carbide dissolution are responsible for the evolution of tensile properties in GH3535 superalloy after different solution heat treatments.
2016, 45(6):1588-1592.
Abstract:
Superelastic behavior and deformation process of a near beta Ti-3Zr-2Sn-3Mo-25Nb alloy sheet under the different heat treatments were investigated. The results show that the alloy has a certain surperelasciticy at solution treatment and aging treatment, especially the superelasciticy of the alloy is the best at solution treatment above the phase transition temperature, and now the maximum volume fiction of the stress induced martensite is observed. But both the precipitated ω phase and the fine α phase after solution treatment and aging treatment hinder the formation of the stress induced martensite, make the elasticity and the plasticity decrease. The studies also found that the proper predeformation on the sheets could improve superelasticity.
Superelastic behavior and deformation process of a near beta Ti-3Zr-2Sn-3Mo-25Nb alloy sheet under the different heat treatments were investigated. The results show that the alloy has a certain surperelasciticy at solution treatment and aging treatment, especially the superelasciticy of the alloy is the best at solution treatment above the phase transition temperature, and now the maximum volume fiction of the stress induced martensite is observed. But both the precipitated ω phase and the fine α phase after solution treatment and aging treatment hinder the formation of the stress induced martensite, make the elasticity and the plasticity decrease. The studies also found that the proper predeformation on the sheets could improve superelasticity.
2016, 45(6):1593-1599.
Abstract:
The pure vanadium metal thin films were fabricated on the SnO2 doped F conductive glass（FTO） substrates by DC magnetron sputtering at room temperature, then the VO2 /FTO composite films were prepared by annealing process in a mixture of N2 and O2. The structure and optical-electrical properties of the composite films were analyzed by instruments. AFM results show that the crystallinity of the thin film is improved significantly with smooth and uniform surface morphology. Results show that VO2 /FTO composite films do not change the preferred orientation growth of VO2 thin films, but significantly change its surface morphology characteristics. Compared with the VO2 thin films that the phase transition temperature of the VO2 /FTO composite films is decreased about 20℃, the width of thermal hysteresis is narrowed by about 5℃, and the infrared transmittances before and after phase transition are 45% and 22% respectively. The resistivity variation is up to three orders of magnitude before and after transition. This brings about many new opportunities for optoelectronic devices and industrial production.
The pure vanadium metal thin films were fabricated on the SnO2 doped F conductive glass（FTO） substrates by DC magnetron sputtering at room temperature, then the VO2 /FTO composite films were prepared by annealing process in a mixture of N2 and O2. The structure and optical-electrical properties of the composite films were analyzed by instruments. AFM results show that the crystallinity of the thin film is improved significantly with smooth and uniform surface morphology. Results show that VO2 /FTO composite films do not change the preferred orientation growth of VO2 thin films, but significantly change its surface morphology characteristics. Compared with the VO2 thin films that the phase transition temperature of the VO2 /FTO composite films is decreased about 20℃, the width of thermal hysteresis is narrowed by about 5℃, and the infrared transmittances before and after phase transition are 45% and 22% respectively. The resistivity variation is up to three orders of magnitude before and after transition. This brings about many new opportunities for optoelectronic devices and industrial production.
2016, 45(6):1600-1604.
Abstract:
The inhibition effects of sodium lignosulphonate (SLS) have been studied by means of weight loss method, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM). The results showed that sodium lignosulphonate (SLS) could inhibit effectively the corrosion for AZ31 magnesium alloy in 3.5% NaCl solution, and that the consisting of 4.0 g/L SLS is of an inhibition efficiency higher to 75.4%. SLS is an anion inhibitor and the adsorption of SLS on the AZ31 magnesium alloy surface obeys to the Langmuir adsorption isotherm which due to the adsorption free energy ?G0 and the Arrhenius active energy Ea.
The inhibition effects of sodium lignosulphonate (SLS) have been studied by means of weight loss method, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM). The results showed that sodium lignosulphonate (SLS) could inhibit effectively the corrosion for AZ31 magnesium alloy in 3.5% NaCl solution, and that the consisting of 4.0 g/L SLS is of an inhibition efficiency higher to 75.4%. SLS is an anion inhibitor and the adsorption of SLS on the AZ31 magnesium alloy surface obeys to the Langmuir adsorption isotherm which due to the adsorption free energy ?G0 and the Arrhenius active energy Ea.
2016, 45(6):1605-1608.
Abstract:
In this article, the microstructure evolution and mechanical property of Ti-22Al-25Nb（at. %） alloy after different phase region isothermally forging and heat treatment were studied. The results indicated that as the isothermally forging temperature increased from 980℃（α2＋O＋B2 three phase region) to 1060℃（B2 phase region), the microstructures of alloys showed that equiaxed microstructures, duplex microstructures, and bimodal size lamellar O microstructures. The size and volume fraction of each phases couble be controlled by heat-treatment schedule. The mechanical properties of alloys showed that bimodal size lamellar O microstructures have the biggest strength but the poor ductility; however, equiaxed microstructures have the biggest ductility but the poor strength. The equiaxed microstructures have the worst creep resistance, the duplex microstructures and the bimodal size lamellar O microstructures have similar creep resistance.
In this article, the microstructure evolution and mechanical property of Ti-22Al-25Nb（at. %） alloy after different phase region isothermally forging and heat treatment were studied. The results indicated that as the isothermally forging temperature increased from 980℃（α2＋O＋B2 three phase region) to 1060℃（B2 phase region), the microstructures of alloys showed that equiaxed microstructures, duplex microstructures, and bimodal size lamellar O microstructures. The size and volume fraction of each phases couble be controlled by heat-treatment schedule. The mechanical properties of alloys showed that bimodal size lamellar O microstructures have the biggest strength but the poor ductility; however, equiaxed microstructures have the biggest ductility but the poor strength. The equiaxed microstructures have the worst creep resistance, the duplex microstructures and the bimodal size lamellar O microstructures have similar creep resistance.
2016, 45(6):1609-1614.
Abstract:
In this paper, the Fe3O4 magnetic nanoparticles were prepared by coprecipitation method with sodium oleate as surfactant modification, and magnetic fluid was prepared with silicon oil as the carrier. The influence of different adding ammonia orders and different adding speed on the property of magnetic fluid was studied. The Fe3O4 magnetic fluid was tested by VSM, the settlement after standing and TEM. The reslut showed that when the ammonia added before the sodium oleate, the dispersivity of the magnetic liquid is the best and the saturation magnetization is 11.4emu/g. Furthermore, with dripping ammonia in a speed of 10ml/min before adding the sodium oleate, the dispersivity of the magnetic liquid is better and the saturation magnetization is 14.3emu/g.
In this paper, the Fe3O4 magnetic nanoparticles were prepared by coprecipitation method with sodium oleate as surfactant modification, and magnetic fluid was prepared with silicon oil as the carrier. The influence of different adding ammonia orders and different adding speed on the property of magnetic fluid was studied. The Fe3O4 magnetic fluid was tested by VSM, the settlement after standing and TEM. The reslut showed that when the ammonia added before the sodium oleate, the dispersivity of the magnetic liquid is the best and the saturation magnetization is 11.4emu/g. Furthermore, with dripping ammonia in a speed of 10ml/min before adding the sodium oleate, the dispersivity of the magnetic liquid is better and the saturation magnetization is 14.3emu/g.
2016, 45(6):1615-1619.
Abstract:
Thermal oxidation (TO) treatments were conducted on Ti6Al4V under 873～1023 K for 10 h. Microstructural characteristics of the TO layers were analyzed using X-ray diffraction (XRD), glow discharge optical emission spectrometer analysis (GDOES) and optical microscope (OM). Effect of TO temperature on wear resistance of Ti6Al4V was estimated on MFT-R4000 reciprocating friction-wear testing machine. The results showed that the obtained TO layers were uniform and continuous. TO temperatures had significant impacts on the formation, surface hardness and wear resistance on TO layers. The TO layer produced at 973 K exhibited the best wear resistance indicating by higher surface hardness, lower mass loss and narrower wear trace in comparison with other TO layers.
Thermal oxidation (TO) treatments were conducted on Ti6Al4V under 873～1023 K for 10 h. Microstructural characteristics of the TO layers were analyzed using X-ray diffraction (XRD), glow discharge optical emission spectrometer analysis (GDOES) and optical microscope (OM). Effect of TO temperature on wear resistance of Ti6Al4V was estimated on MFT-R4000 reciprocating friction-wear testing machine. The results showed that the obtained TO layers were uniform and continuous. TO temperatures had significant impacts on the formation, surface hardness and wear resistance on TO layers. The TO layer produced at 973 K exhibited the best wear resistance indicating by higher surface hardness, lower mass loss and narrower wear trace in comparison with other TO layers.
47 Influences of Melt Superheating Treatment on Microstructure and Properties of AZ91D Magnesium Alloy
2016, 45(6):1620-1624.
Abstract:
In this paper, the influences of the melt superheating temperature on the solidification structure and mechanical properties of AZ91D magnesium are studied by a home-made electrical resistance furnace. The results show that, with the increase of melt superheating temperature, the as-cast structure of AZ91D alloy changes from dendrite morphology into equiaxed grain morphology, the grain size gradually decreases, while the change of the grain size is not obviously when the melt superheating temperature exceeds 850℃. With the enhancement of melt superheating temperature, the tensile strength, offset yield strength and specific elongation increase firstly and then decreases. The mechanical properties of AZ91D reach the maximum. The analysis of DSC show that the increase the melt superheating temperature makes the beginning solidification temperature reduce, shrink the freezing range, decrease the critical nucleus radius, increase the degree of supercooling of the melt and enhance the heterogeneous nucleation rate, these are the primary reason of grain refinement in magnesium alloy. Increasing the superheating temperature will lead to the increase of the eutectic transformation temperature, hence the eutectic phase is coarse.
In this paper, the influences of the melt superheating temperature on the solidification structure and mechanical properties of AZ91D magnesium are studied by a home-made electrical resistance furnace. The results show that, with the increase of melt superheating temperature, the as-cast structure of AZ91D alloy changes from dendrite morphology into equiaxed grain morphology, the grain size gradually decreases, while the change of the grain size is not obviously when the melt superheating temperature exceeds 850℃. With the enhancement of melt superheating temperature, the tensile strength, offset yield strength and specific elongation increase firstly and then decreases. The mechanical properties of AZ91D reach the maximum. The analysis of DSC show that the increase the melt superheating temperature makes the beginning solidification temperature reduce, shrink the freezing range, decrease the critical nucleus radius, increase the degree of supercooling of the melt and enhance the heterogeneous nucleation rate, these are the primary reason of grain refinement in magnesium alloy. Increasing the superheating temperature will lead to the increase of the eutectic transformation temperature, hence the eutectic phase is coarse.
2016, 45(6):1625-1630.
Abstract:
On the basis of using sodium citrate as a reducing agent to reduce chloroauric acid, a synthesis-controlled method of gold nanoparticles is presented by using the pulsed micromixing technology actuated by PZT actuators. The synthesis mechanism of gold nanoparticles and working principle of pulsed micromixing are analysed. According to different concentration ratio (Na3C6H5O7:HAuCl4) and pulsed mixing frequency, the relevant controlled synthesis tests of gold nanoparticles are designed and carried out. The characteristics of obtained specimen including optical properties, particle size, particle deviation and monodispersity are characterized using UV-vis and TEM. The effect of concentration ratio and frequency to the test results is analyzed. The test results show that controlled synthesis of gold nanoparticles can be realized using the pulsed micromixing method based on piezoelectric actuation, by controlling the concentration ratio of two preparations and pulsed mixing frequency.
On the basis of using sodium citrate as a reducing agent to reduce chloroauric acid, a synthesis-controlled method of gold nanoparticles is presented by using the pulsed micromixing technology actuated by PZT actuators. The synthesis mechanism of gold nanoparticles and working principle of pulsed micromixing are analysed. According to different concentration ratio (Na3C6H5O7:HAuCl4) and pulsed mixing frequency, the relevant controlled synthesis tests of gold nanoparticles are designed and carried out. The characteristics of obtained specimen including optical properties, particle size, particle deviation and monodispersity are characterized using UV-vis and TEM. The effect of concentration ratio and frequency to the test results is analyzed. The test results show that controlled synthesis of gold nanoparticles can be realized using the pulsed micromixing method based on piezoelectric actuation, by controlling the concentration ratio of two preparations and pulsed mixing frequency.
2016, 45(6):1631-1635.
Abstract:
In the present work, the hot compressive deformation test of TiNiCr alloy was carried out by using Gleeble-3500 in the strain rate range of 0.001 ~1s-1 and temperature range of 600~900℃. The microstructures of TiNiCr after deformation and the true stress-strain curves were studied. The results show that, the true stress-strain curves of TiNiCr alloy are affected by the work hardening and softening effect, the flow stress decreases with increasing temperature and decreasing strain rate. During hot compression, the dislocations which result in the hardening decrease because of the softening effect. Dynamic recrystallization occurs under all the deformation conditions and new grains are formed through grain boundaries bulging. The higher the temperature is and the lower strain rate is, the more obvious the dynamic recrystallization tendency is, the larger the grain size is and the more important role the dynamic recrystallization plays in the softening mechanism. TiNiCr alloy is different from the traditional non-intermetallic compounds, the softening mechanism can not be speculated only through the true stress-strain curves.
In the present work, the hot compressive deformation test of TiNiCr alloy was carried out by using Gleeble-3500 in the strain rate range of 0.001 ~1s-1 and temperature range of 600~900℃. The microstructures of TiNiCr after deformation and the true stress-strain curves were studied. The results show that, the true stress-strain curves of TiNiCr alloy are affected by the work hardening and softening effect, the flow stress decreases with increasing temperature and decreasing strain rate. During hot compression, the dislocations which result in the hardening decrease because of the softening effect. Dynamic recrystallization occurs under all the deformation conditions and new grains are formed through grain boundaries bulging. The higher the temperature is and the lower strain rate is, the more obvious the dynamic recrystallization tendency is, the larger the grain size is and the more important role the dynamic recrystallization plays in the softening mechanism. TiNiCr alloy is different from the traditional non-intermetallic compounds, the softening mechanism can not be speculated only through the true stress-strain curves.
2016, 45(6):1636-1640.
Abstract:
Porous metal fibrous materials is a new type of light porous metal materials and its mechanical properties is one of key performance affecting strongly its application. The paper foucused on the status of the tensile, the shear, the compressive and the impact properties of porous metal fibrous materials and the research progress on the stress wave propagating in the material was briefly discussed. In order to expand the application fields of porous metal fibrous materials, its dynamic shocking performance and the stress wave propagation and attenuation in the material should be studied systemly in the future.
Porous metal fibrous materials is a new type of light porous metal materials and its mechanical properties is one of key performance affecting strongly its application. The paper foucused on the status of the tensile, the shear, the compressive and the impact properties of porous metal fibrous materials and the research progress on the stress wave propagating in the material was briefly discussed. In order to expand the application fields of porous metal fibrous materials, its dynamic shocking performance and the stress wave propagation and attenuation in the material should be studied systemly in the future.
