Volume 40,Issue 6,2011 Table of Contents
Yu Zeming
,
Odier P
,
Ortega L
,
Zhou Lian
,
Zhang Pingxiang
,
Lu Yafeng
,
Jin Lihua
,
Li Chengshan
,
Liu Xianghong
2011, 40(6):941-945.
Abstract:
The influences of electro-depositing parameters on the formation of cube-textured Ni layer on Cu tape were studied. Results show that the cube texture can be obtained when the cathode potential is low enough and the pH value of electrolyte is in an appropriate range from 3 to 4. The influences of electro-depositing parameters could be explained by the geometrical selection theory. Finally, the thermal stability of texture of Ni layers was also investigated.
The influences of electro-depositing parameters on the formation of cube-textured Ni layer on Cu tape were studied. Results show that the cube texture can be obtained when the cathode potential is low enough and the pH value of electrolyte is in an appropriate range from 3 to 4. The influences of electro-depositing parameters could be explained by the geometrical selection theory. Finally, the thermal stability of texture of Ni layers was also investigated.
2011, 40(6):946-950.
Abstract:
The microstructure evolution of TC11 alloy with lamellar structures deformed at temperatures of 980-850 °C and strain rates of 0.001, 0.01 and 0.1 s-1, and the static structure evolution and mechanism of the alloy annealed at different temperatures were investigated. The results show that dynamic recrystallization process at higher reduction, higher temperature and lower strain rate is almost complete, and the globularized fraction of the annealed microstructure mainly depends on the dynamic recrystallization during deformation. But the dynamic recrystallization process at lower reduction, lower temperature and higher strain rate is restrained, and the globularized fraction of the annealed structure depends on both of the deformation state and the static recrystallization process during annealing. a-grain size mainly depends on annealing temperature and holding time mainly. EBSD tests of dynamic and static globularized microstructures show that the mechanism of static globularization during annealing involves the static recrystallization of b-phase and the static recovery of a-phase, and subsequent globularization and coarsening.
The microstructure evolution of TC11 alloy with lamellar structures deformed at temperatures of 980-850 °C and strain rates of 0.001, 0.01 and 0.1 s-1, and the static structure evolution and mechanism of the alloy annealed at different temperatures were investigated. The results show that dynamic recrystallization process at higher reduction, higher temperature and lower strain rate is almost complete, and the globularized fraction of the annealed microstructure mainly depends on the dynamic recrystallization during deformation. But the dynamic recrystallization process at lower reduction, lower temperature and higher strain rate is restrained, and the globularized fraction of the annealed structure depends on both of the deformation state and the static recrystallization process during annealing. a-grain size mainly depends on annealing temperature and holding time mainly. EBSD tests of dynamic and static globularized microstructures show that the mechanism of static globularization during annealing involves the static recrystallization of b-phase and the static recovery of a-phase, and subsequent globularization and coarsening.
2011, 40(6):951-956.
Abstract:
A finite element (FE) model of preforming process of TA15 Ti-alloy complex components has been established based on DEFORM-3D platform. Combined with the experiments, the preforming process and typical forming defects have been analyzed. An excellent preform with good macroscopical forming quality, uniform and fine microstructure has been fabricated using an optimized billet with the proper initial shape, which is acquired by a systematic stepwise reverse optimization method, effectively avoiding the defects of underfilling and folding in the preforming process. The preforming experiment was carried out based on the optimized initial billet and the result of optimization has been verified which is reasonable and reliable.
A finite element (FE) model of preforming process of TA15 Ti-alloy complex components has been established based on DEFORM-3D platform. Combined with the experiments, the preforming process and typical forming defects have been analyzed. An excellent preform with good macroscopical forming quality, uniform and fine microstructure has been fabricated using an optimized billet with the proper initial shape, which is acquired by a systematic stepwise reverse optimization method, effectively avoiding the defects of underfilling and folding in the preforming process. The preforming experiment was carried out based on the optimized initial billet and the result of optimization has been verified which is reasonable and reliable.
2011, 40(6):957-960.
Abstract:
Hot-hydrostatic extrusion and hot torsion (HE+HT) were applied to the processing of the as-sintered tungsten heavy alloy (WHA). The dynamic mechanical properties of the WHA processed by HE+HT and the microstructural evolution within adiabatic shear band (ASB) were systematically investigated. The results show that the WHA susceptibility to ASB is much improved, and localized shear bands can be formed in specimens. TEM analysis of ASB shows that the multiplication and rearrangement of dislocation play dominate roles in the dynamic recrystallization (DRX) process within ASB of WHA, and the nano-scaled equiaxed-recrystallized grains within ASB can be formed via repeating the processes including dislocation multiplication, dislocation rearrangement and dislocation annihilation. The investigation result of observed DRX of the WHA firmly supports the rotational dynamic recrystallization (RDR) mechanism in metals.
Hot-hydrostatic extrusion and hot torsion (HE+HT) were applied to the processing of the as-sintered tungsten heavy alloy (WHA). The dynamic mechanical properties of the WHA processed by HE+HT and the microstructural evolution within adiabatic shear band (ASB) were systematically investigated. The results show that the WHA susceptibility to ASB is much improved, and localized shear bands can be formed in specimens. TEM analysis of ASB shows that the multiplication and rearrangement of dislocation play dominate roles in the dynamic recrystallization (DRX) process within ASB of WHA, and the nano-scaled equiaxed-recrystallized grains within ASB can be formed via repeating the processes including dislocation multiplication, dislocation rearrangement and dislocation annihilation. The investigation result of observed DRX of the WHA firmly supports the rotational dynamic recrystallization (RDR) mechanism in metals.
2011, 40(6):961-966.
Abstract:
GH4199 alloy was treated by high density electropulsing for different time, and the microstructure evolution and tensile properties were examined. The results show that the diffusion of solute atoms in GH4199 alloy can be strongly accelerated by electropulsing. The growth activation energy of γ′ phase of 89.86 kJ/mol in the alloy electropulsing-treated, decreases by 64.31 % compared with that normally aged, which accelerates the precipitation and the growth of both the γ′ phase and carbides on the grain boundary of the alloy. The strength of GH4199 alloy increases with increasing of electropulsing treatment time, and the plasticity has no obvious change. The growth of γ′ phase and the precipitation of carbides on the grain boundary is the main reason for obstructing the dislocation motion and improving the plastic deformation resistance of the alloy. The piled-up dislocations can go through the grain boundary across the gap of carbides which is distributed on the grain boundary in chainlike form, and no degradation of the plasticity of GH4199 alloy appears.
GH4199 alloy was treated by high density electropulsing for different time, and the microstructure evolution and tensile properties were examined. The results show that the diffusion of solute atoms in GH4199 alloy can be strongly accelerated by electropulsing. The growth activation energy of γ′ phase of 89.86 kJ/mol in the alloy electropulsing-treated, decreases by 64.31 % compared with that normally aged, which accelerates the precipitation and the growth of both the γ′ phase and carbides on the grain boundary of the alloy. The strength of GH4199 alloy increases with increasing of electropulsing treatment time, and the plasticity has no obvious change. The growth of γ′ phase and the precipitation of carbides on the grain boundary is the main reason for obstructing the dislocation motion and improving the plastic deformation resistance of the alloy. The piled-up dislocations can go through the grain boundary across the gap of carbides which is distributed on the grain boundary in chainlike form, and no degradation of the plasticity of GH4199 alloy appears.
2011, 40(6):967-972.
Abstract:
Abstract: The (V-W-Ti-O)x (Cu-Al-O)1-x (Ce-O)0.03, (x=0.9, 0.8) deNOx monolithic catalysts were prepared by low temperature co-sintering (LTC) within the sintering temperature range of 650-850 °C. The effects of sintering temperature on the mechanical strength, porosity and water absorption of the monolithic catalysts and the effect of reaction temperature on catalytic activity were investigated. The microscopic structure of the catalysts was analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and fourier infrared spectroscopic analysis (FT-IR). Results show that catalysts are porous in micro-structure and grains are distributed uniformly. The crystallographic forms are mainly TiO2 (rutile), TiVO4, WV2O6, CeVO4, Cu2V2O7, AlV2O4, CuAlMnO4 and Cu1.9V12O29. For the reforming monolithic catalysts sintered at 700 °C for 2 h, the two-component catalysts exhibit high catalytic activities in the low temperature range of 100-200 °C and their bending strength reaches to 45.5 MPa. The NO conversion of (V-W-Ti-O)0.8 (Cu-Al-O)0.2 (Ce-O)0.03 monolithic catalyst corresponds to 75.9% at reactor temperature of 150 °C.
Abstract: The (V-W-Ti-O)x (Cu-Al-O)1-x (Ce-O)0.03, (x=0.9, 0.8) deNOx monolithic catalysts were prepared by low temperature co-sintering (LTC) within the sintering temperature range of 650-850 °C. The effects of sintering temperature on the mechanical strength, porosity and water absorption of the monolithic catalysts and the effect of reaction temperature on catalytic activity were investigated. The microscopic structure of the catalysts was analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and fourier infrared spectroscopic analysis (FT-IR). Results show that catalysts are porous in micro-structure and grains are distributed uniformly. The crystallographic forms are mainly TiO2 (rutile), TiVO4, WV2O6, CeVO4, Cu2V2O7, AlV2O4, CuAlMnO4 and Cu1.9V12O29. For the reforming monolithic catalysts sintered at 700 °C for 2 h, the two-component catalysts exhibit high catalytic activities in the low temperature range of 100-200 °C and their bending strength reaches to 45.5 MPa. The NO conversion of (V-W-Ti-O)0.8 (Cu-Al-O)0.2 (Ce-O)0.03 monolithic catalyst corresponds to 75.9% at reactor temperature of 150 °C.
2011, 40(6):973-977.
Abstract:
The nickel-based alloys with different Nb contents were deposited on AISI 1045 carbon steel by laser cladding. The effect of Nb on the microstructures of the nickel-based alloy coatings was investigated using scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The result show that the microstructures of the Nb-modified nickel-based alloy coatings are mainly composed of γ-Ni dendrites, interdendritic eutectics, CrB type chromium borides, and dispersed NbC particles. It is found that the addition of Nb will lead to the precipitation of the NbC particles and M23C6 type carbides instead of the M7C3, and M23C6 type carbides can be observed in the Nb-free nickel-based alloy coating. The microhardness and wear resistance of the coatings increase with the increase of Nb contents. The improvement of the wear resistance of the Nb-modified nickel-based alloy coatings is attributed to the microstructural change and phase variation.
The nickel-based alloys with different Nb contents were deposited on AISI 1045 carbon steel by laser cladding. The effect of Nb on the microstructures of the nickel-based alloy coatings was investigated using scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The result show that the microstructures of the Nb-modified nickel-based alloy coatings are mainly composed of γ-Ni dendrites, interdendritic eutectics, CrB type chromium borides, and dispersed NbC particles. It is found that the addition of Nb will lead to the precipitation of the NbC particles and M23C6 type carbides instead of the M7C3, and M23C6 type carbides can be observed in the Nb-free nickel-based alloy coating. The microhardness and wear resistance of the coatings increase with the increase of Nb contents. The improvement of the wear resistance of the Nb-modified nickel-based alloy coatings is attributed to the microstructural change and phase variation.
2011, 40(6):978-982.
Abstract:
In-situ TiC/Ti6Al4V composites were prepared by a melting-casting method and the effects of Zr addition on the microstructure, compression property and abrasive property of the TiC/Ti6Al4V composites were studied. The results show that when the Zr addition content is in the range of 1%-4% (mass fraction, similarly hereinafter), the morphology of the primary TiC in the composites is dendrite, with the petal-shape, piece-shape or palpus-shape eutectic TiC around the primary TiC. The average size of the primary TiC decreases, the amount of eutectic TiC increases and the abrasive property and compression property increase gradually with increasing Zr content. When the Zr content is 6%-10%, the primary TiC becomes developed again, and the abrasive property and compression property decrease with the increasing of Zr content. The compression strength of the composites is up to the peak value when the Zr content is 4%.
In-situ TiC/Ti6Al4V composites were prepared by a melting-casting method and the effects of Zr addition on the microstructure, compression property and abrasive property of the TiC/Ti6Al4V composites were studied. The results show that when the Zr addition content is in the range of 1%-4% (mass fraction, similarly hereinafter), the morphology of the primary TiC in the composites is dendrite, with the petal-shape, piece-shape or palpus-shape eutectic TiC around the primary TiC. The average size of the primary TiC decreases, the amount of eutectic TiC increases and the abrasive property and compression property increase gradually with increasing Zr content. When the Zr content is 6%-10%, the primary TiC becomes developed again, and the abrasive property and compression property decrease with the increasing of Zr content. The compression strength of the composites is up to the peak value when the Zr content is 4%.
9 Formation Mechanism and Growth Law of Diffusion Solution Zone between Al/Ti Liquid/Solid Interface
2011, 40(6):983-986.
Abstract:
Al/Ti diffusion couples were made by embedded technology and diffusion heat treatment was carried out between the melting point of Al and that of Ti. The microstructure evolution, formation mechanism and growth law of Al/Ti diffusion solution zone were investigated. The results show that the microstructure of the diffusion solution zone after heat treatment is the mixture of TiAl3 and Al solid solution with a few Ti; TiAl3 forms first and is the only new phase during heat treatment. The growth mechanism and direction of the diffusion solution zone change with prolonging of treating time; first, its growth is controlled by reaction regime and the growth direction is to Ti substrate, and the growth rate and holding time have linearity relation; afterwards, its growth mechanism changes to diffusion regime and the growth direction is to Al substrate, and the growth rate and holding time have parabola relation. For certain time, the thickness of diffusion solution zone and the treating temperature have the index relation.
Al/Ti diffusion couples were made by embedded technology and diffusion heat treatment was carried out between the melting point of Al and that of Ti. The microstructure evolution, formation mechanism and growth law of Al/Ti diffusion solution zone were investigated. The results show that the microstructure of the diffusion solution zone after heat treatment is the mixture of TiAl3 and Al solid solution with a few Ti; TiAl3 forms first and is the only new phase during heat treatment. The growth mechanism and direction of the diffusion solution zone change with prolonging of treating time; first, its growth is controlled by reaction regime and the growth direction is to Ti substrate, and the growth rate and holding time have linearity relation; afterwards, its growth mechanism changes to diffusion regime and the growth direction is to Al substrate, and the growth rate and holding time have parabola relation. For certain time, the thickness of diffusion solution zone and the treating temperature have the index relation.
2011, 40(6):987-990.
Abstract:
The change of oxygen was studied for the TZM molybdenum alloys with addition of active metal element and carbon after vacuum sintering. The mechanism of deoxidation of molybdenum alloys was analyzed through the thermodynamic calculation. The results show that in the sintering process of powder metallurgical TZM, there are two kinds of deoxidation mechanisms. One is that metal oxide compound in TZM react with the carbon to produce CO and metal carbide; the other is that the disproportionting reaction of MoO2 occurs at high temperature to produce metal Mo and MoO3 gas and the gas is drawn out by the vacuum system. Improving the vacuum degree of the furnace and reducing the partial pressure of product gas can decrease reaction temperature and is good for deoxidation.
The change of oxygen was studied for the TZM molybdenum alloys with addition of active metal element and carbon after vacuum sintering. The mechanism of deoxidation of molybdenum alloys was analyzed through the thermodynamic calculation. The results show that in the sintering process of powder metallurgical TZM, there are two kinds of deoxidation mechanisms. One is that metal oxide compound in TZM react with the carbon to produce CO and metal carbide; the other is that the disproportionting reaction of MoO2 occurs at high temperature to produce metal Mo and MoO3 gas and the gas is drawn out by the vacuum system. Improving the vacuum degree of the furnace and reducing the partial pressure of product gas can decrease reaction temperature and is good for deoxidation.
11 Dry Tribological Properties of Magnetron Sputtered SiC Films on Nanocrystalline Titanium Substrate
2011, 40(6):991-994.
Abstract:
SiC (carbon nitride) thin films were deposited on nanocrystalline titanium substrate (produced by severe plastic deformation) by magnetron sputtering technique at room temperature. The microstructure, nano-indentation and friction/wear properties of the SiC films were investigated. The results show that the SiC films are of nano-scale domain features for surface morphology, a large amount of Si-C bonds, good adhesion (with obvious and gradual film-substrate element diffusions as well as small film-substrate elastic modulus difference), low nano-hardness (10.62 GPa), low Young's modulus (83.34 GPa) and high hardness-to-modulus ratio (0.128). When sliding against Si3N4 ball (2 mm in radius) under room-temperature air condition and 1.96 N load, the SiC films exhibit the friction coefficient of about 0.162, and the special wear rate in the magnitude order of 10-5 mm3·m-1·N-1 with no film cracking and interface delaminating.
SiC (carbon nitride) thin films were deposited on nanocrystalline titanium substrate (produced by severe plastic deformation) by magnetron sputtering technique at room temperature. The microstructure, nano-indentation and friction/wear properties of the SiC films were investigated. The results show that the SiC films are of nano-scale domain features for surface morphology, a large amount of Si-C bonds, good adhesion (with obvious and gradual film-substrate element diffusions as well as small film-substrate elastic modulus difference), low nano-hardness (10.62 GPa), low Young's modulus (83.34 GPa) and high hardness-to-modulus ratio (0.128). When sliding against Si3N4 ball (2 mm in radius) under room-temperature air condition and 1.96 N load, the SiC films exhibit the friction coefficient of about 0.162, and the special wear rate in the magnitude order of 10-5 mm3·m-1·N-1 with no film cracking and interface delaminating.
2011, 40(6):995-999.
Abstract:
A Mg-11Gd-1Y-0.5Zn(wt%) alloy was coated by different micro-arc oxidation (MAO) processes, and the coating structure and corrosion resistance of the alloy were studied by scanning electron microscopy (SEM), glancing angle X-ray diffraction (GAXRD) and various electrochemical methods. The micro-arc oxidation process used for the alloy consists of 3 stages, corresponding with different coating structures. In the initial stage, the coating thickness is linearly increased and controlled by electrochemical polarization. In the second stage, the coating is mainly inward growth and accords with parabolic regularity. In the third stage, the loose coating is formed and controlled by local arc light. The loose coating is mainly composed of MgSiO3 and the compact coating is mainly of MgO. From the stage of micro-arc oxidation to that of local arc light, the corrosion resistance of the coated alloy is firstly increased and then decreased. The satisfied corrosion resistance corresponds to the coating time ranging from 7 to12 min.
A Mg-11Gd-1Y-0.5Zn(wt%) alloy was coated by different micro-arc oxidation (MAO) processes, and the coating structure and corrosion resistance of the alloy were studied by scanning electron microscopy (SEM), glancing angle X-ray diffraction (GAXRD) and various electrochemical methods. The micro-arc oxidation process used for the alloy consists of 3 stages, corresponding with different coating structures. In the initial stage, the coating thickness is linearly increased and controlled by electrochemical polarization. In the second stage, the coating is mainly inward growth and accords with parabolic regularity. In the third stage, the loose coating is formed and controlled by local arc light. The loose coating is mainly composed of MgSiO3 and the compact coating is mainly of MgO. From the stage of micro-arc oxidation to that of local arc light, the corrosion resistance of the coated alloy is firstly increased and then decreased. The satisfied corrosion resistance corresponds to the coating time ranging from 7 to12 min.
2011, 40(6):1000-1004.
Abstract:
The influence of Y addition on cyclic oxidation behaviors of Ti45Al8Nb alloys (at%) was investigated in air at 900 oC by SEM, XRD and EDS. Results show that proper Y addition can markedly increase cyclic oxidation resistance of the alloys. The grain sizes are gradually decreased with the increasing Y content. In cyclic oxidation tests all Y added alloys except Ti45Al8Nb0.1Y show no obvious scale spallation after 1000 cycles while Y free alloy shows serious spallation even after 300 cycles. Y addition enhances the adhesion between the oxide film and the substrate. However, alloys with excessive Y suffer severe internal oxidation by providing rapid diffusion paths for O in the form of coarse Y2O3 particles at oxide grain boundary.
The influence of Y addition on cyclic oxidation behaviors of Ti45Al8Nb alloys (at%) was investigated in air at 900 oC by SEM, XRD and EDS. Results show that proper Y addition can markedly increase cyclic oxidation resistance of the alloys. The grain sizes are gradually decreased with the increasing Y content. In cyclic oxidation tests all Y added alloys except Ti45Al8Nb0.1Y show no obvious scale spallation after 1000 cycles while Y free alloy shows serious spallation even after 300 cycles. Y addition enhances the adhesion between the oxide film and the substrate. However, alloys with excessive Y suffer severe internal oxidation by providing rapid diffusion paths for O in the form of coarse Y2O3 particles at oxide grain boundary.
2011, 40(6):1005-1009.
Abstract:
he equilibrium precipitated phases and non-equilibrium solidification of GH4133B alloy were studied by Thermo-Calc software, in order to find the theoretical foundation of heat treatment and hot work processing. The microstructure of the alloy was also observed. The results show that the quantitative calculated results of the precipitated temperature and mass fraction of g ￠ phase based on the effect Ti and Al content were acquired. The content of C can affect the M23C6’s mass fraction but have no influence on its precipitated temperature. The content of Cr has a main effect on the M23C6’s precipitated temperature but no influence on its mass fraction. Further study was done on the relation between the content of Ti & Al and the precipitation of η phase. The precipitation and distribution condition during aging treatment of η phase were also proofed by experiments.
he equilibrium precipitated phases and non-equilibrium solidification of GH4133B alloy were studied by Thermo-Calc software, in order to find the theoretical foundation of heat treatment and hot work processing. The microstructure of the alloy was also observed. The results show that the quantitative calculated results of the precipitated temperature and mass fraction of g ￠ phase based on the effect Ti and Al content were acquired. The content of C can affect the M23C6’s mass fraction but have no influence on its precipitated temperature. The content of Cr has a main effect on the M23C6’s precipitated temperature but no influence on its mass fraction. Further study was done on the relation between the content of Ti & Al and the precipitation of η phase. The precipitation and distribution condition during aging treatment of η phase were also proofed by experiments.
2011, 40(6):1010-1014.
Abstract:
The Mg-5%Hg-1%Ga alloy was prepared by melting-casting. Aging at 573-773 K for different time were carried out to ensure the fine dispersion of Mg3Hg compounds. Scanning electron microscopy (SEM), emission spectrometry (ESA) and X-ray diffraction (XRD) were employed to characterize the morphology and distribution of the secondary phase Ma3Hg. The electrochemical and corrosion behaviors of the alloy in 3.5wt% NaCl solution was studied by means of potentiodynamic, galvanostatic and electrochemical impedance spectroscopy (EIS) measurements. The relationship between the Mg3Hg compound and the electrochemical properties of the Mg-5%Hg-1%Ga alloy was discussed. The results demonstrate that when the aging time increases from 15 min to 200 h, the intergranular eutectic of α-Mg and Mg3Hg changes into dispersed Mg3Hg particles in α-Mg matrix. This transition increases electrochemical activity of Mg-5%Hg-1%Ga alloy due to the decreased concentration polarization and charge transfer resistance in the faradaic reaction. The electrochemical homogeneity of the microstructure increases the corrosion resistance of the Mg-5%Hg-1%Ga alloy.
The Mg-5%Hg-1%Ga alloy was prepared by melting-casting. Aging at 573-773 K for different time were carried out to ensure the fine dispersion of Mg3Hg compounds. Scanning electron microscopy (SEM), emission spectrometry (ESA) and X-ray diffraction (XRD) were employed to characterize the morphology and distribution of the secondary phase Ma3Hg. The electrochemical and corrosion behaviors of the alloy in 3.5wt% NaCl solution was studied by means of potentiodynamic, galvanostatic and electrochemical impedance spectroscopy (EIS) measurements. The relationship between the Mg3Hg compound and the electrochemical properties of the Mg-5%Hg-1%Ga alloy was discussed. The results demonstrate that when the aging time increases from 15 min to 200 h, the intergranular eutectic of α-Mg and Mg3Hg changes into dispersed Mg3Hg particles in α-Mg matrix. This transition increases electrochemical activity of Mg-5%Hg-1%Ga alloy due to the decreased concentration polarization and charge transfer resistance in the faradaic reaction. The electrochemical homogeneity of the microstructure increases the corrosion resistance of the Mg-5%Hg-1%Ga alloy.
2011, 40(6):1015-1018.
Abstract:
The crystal parameters and phase composition of Sm2Fe17Nx powders were investigated by means of XRD (X-ray Diffraction Test) and Rietveled method. The results show that the nitrogen atoms preferentially enter 9e crystal sites, and the introduction of them leads to the asymmetric distortion of SmFeN unit cell, resulting in that the occupancy of 6c and 3a sites for rare-earth Sm and 9d sites for Fe atoms are super-saturation, while the 6c, 18f and 18h sites for Fe atoms are possessed incompletely. After heated at 490 oC for 4 h under 0.3 MPa N2 atmosphere, the occupancy factor of nitrogen atoms in the 9e sites is 99.4% and the high-purity and high-nitrogen-content SmFeN powder with 97.9wt% main phase, 0.9wt% Sm2O3 phase, 0.5wt% SmN phase and 0.7wt% α-Fe phase are obtained.
The crystal parameters and phase composition of Sm2Fe17Nx powders were investigated by means of XRD (X-ray Diffraction Test) and Rietveled method. The results show that the nitrogen atoms preferentially enter 9e crystal sites, and the introduction of them leads to the asymmetric distortion of SmFeN unit cell, resulting in that the occupancy of 6c and 3a sites for rare-earth Sm and 9d sites for Fe atoms are super-saturation, while the 6c, 18f and 18h sites for Fe atoms are possessed incompletely. After heated at 490 oC for 4 h under 0.3 MPa N2 atmosphere, the occupancy factor of nitrogen atoms in the 9e sites is 99.4% and the high-purity and high-nitrogen-content SmFeN powder with 97.9wt% main phase, 0.9wt% Sm2O3 phase, 0.5wt% SmN phase and 0.7wt% α-Fe phase are obtained.
2011, 40(6):1019-1024.
Abstract:
The equilibrium phases in P/M superalloy FGH96 were calculated by Thermo-Calc software and the relevant Ni-base superalloy database. The effects of element content in the allowable variation on the precipitation behavior of γ′ and carbides were analyzed. The calculation results show that the equilibrium precipitation phases are γ′, MC, M23C6, MB2, M3B2 and TCP phases. The solution temperature and precipitation amount of γ′ are significantly increased with more Al, Ti and Nb. The amount of carbides and the precipitation temperature of MC are mainly influenced by the content of carbon. The precipitation temperature of carbides is significantly increased with the Al content increasing and the Nb content decreasing; in particular, Al has a more important effect.
The equilibrium phases in P/M superalloy FGH96 were calculated by Thermo-Calc software and the relevant Ni-base superalloy database. The effects of element content in the allowable variation on the precipitation behavior of γ′ and carbides were analyzed. The calculation results show that the equilibrium precipitation phases are γ′, MC, M23C6, MB2, M3B2 and TCP phases. The solution temperature and precipitation amount of γ′ are significantly increased with more Al, Ti and Nb. The amount of carbides and the precipitation temperature of MC are mainly influenced by the content of carbon. The precipitation temperature of carbides is significantly increased with the Al content increasing and the Nb content decreasing; in particular, Al has a more important effect.
18 Preparation and Electrochemical Property of AB3 Type LaMg2Ni9-x-y-zCoxMnyCuz Hydrogen Storage Alloys
2011, 40(6):1025-1028.
Abstract:
AB3 type LaMg2Ni9-x-y-zCoxMnyCuz (x=1.8, 2.1, 2.4, 2.7, 3.0; y=2.1, 2.4, 2.7, 3.0, 3.3; z=0.3, 0.6, 0.9, 1.2, 1.5) hydrogen storage alloys were synthesized by a coprecipitation-reduction-diffusion method according to the orthogonal experimental design. Their discharge capacity and cycle stability were studied and the structure was analyzed by XRD. The results indicate that the maximum discharge capacity of the series of alloys under multielement substitution is higher than the alloys under single element substitution, but the cycle stability decline slightly. Structure analyses show that the main phase of alloys is La4Co3. LaMg2Ni2.7Co2.1Mn2.7Cu1.5 alloy shows the best electrochemical properties in the series of hydrogen storage alloys.
AB3 type LaMg2Ni9-x-y-zCoxMnyCuz (x=1.8, 2.1, 2.4, 2.7, 3.0; y=2.1, 2.4, 2.7, 3.0, 3.3; z=0.3, 0.6, 0.9, 1.2, 1.5) hydrogen storage alloys were synthesized by a coprecipitation-reduction-diffusion method according to the orthogonal experimental design. Their discharge capacity and cycle stability were studied and the structure was analyzed by XRD. The results indicate that the maximum discharge capacity of the series of alloys under multielement substitution is higher than the alloys under single element substitution, but the cycle stability decline slightly. Structure analyses show that the main phase of alloys is La4Co3. LaMg2Ni2.7Co2.1Mn2.7Cu1.5 alloy shows the best electrochemical properties in the series of hydrogen storage alloys.
19 Effect of Concentration and Particle-Size of Silver Nanoparticles on the Catalytic Nitro-Compound
2011, 40(6):1029-1032.
Abstract:
Ag nanoparticles were employed as catalyst and their effect on the reaction rate of the nitro-compound were investigated. Results show that Ag nanoparticles can greatly accelerate the reduction of nitro-compound at room temperature, and the nitro-compound with positive charges has higher catalytic reaction rate than that with negative charges. More Ag nanoparticles lead to higher reaction rate; however, the amount should be limited due to the properties of the nanoparticles. The bigger the Ag nanoparticle size is, the higher the reaction rate is.
Ag nanoparticles were employed as catalyst and their effect on the reaction rate of the nitro-compound were investigated. Results show that Ag nanoparticles can greatly accelerate the reduction of nitro-compound at room temperature, and the nitro-compound with positive charges has higher catalytic reaction rate than that with negative charges. More Ag nanoparticles lead to higher reaction rate; however, the amount should be limited due to the properties of the nanoparticles. The bigger the Ag nanoparticle size is, the higher the reaction rate is.
2011, 40(6):1033-1037.
Abstract:
Microstructure and hydrogen permeability of Nb-Ni-Ti alloy membranes for hydrogen separation were investigated. XRD and SEM were employed to characterize the phases and microstructure of Nb-Ni-Ti ternary alloys; hydrogen diffusion coefficients of these membranes with different thickness, composition or microstructure, were measured in Devanathan-Stachurski dual-cell system. The results indicate that hydrogen diffusion coefficient increases with the increasing thickness of these membranes. Basically these alloys are all of two-phase, i.e. the primary bcc-Nb(Ni,Ti) solid solution phase and the eutectic phase of bcc-Nb(Ni,Ti)+β2-NiTi, while just a small amount of NiTi2 phase is observed in very few samples. Microstructure and composition play an important role on hydrogen diffusion. Hydrogen diffusion coefficient is increased with the increase of the content of solid solution phase; the addition of Ni and Ti lead to the variety of eutectic phase composition; the presence of NiTi phase and NiTi2 phase decreases the hydrogen diffusion coefficient, but benefits the resistance to hydrogen embrittlement induced by the crystal expansion/contraction during atomic hydrogen permeation/release. Hydrogen diffusion coefficient of Nb-Ni-Ti alloy membranes falls in the magnitude of 10-9 m2/s.
Microstructure and hydrogen permeability of Nb-Ni-Ti alloy membranes for hydrogen separation were investigated. XRD and SEM were employed to characterize the phases and microstructure of Nb-Ni-Ti ternary alloys; hydrogen diffusion coefficients of these membranes with different thickness, composition or microstructure, were measured in Devanathan-Stachurski dual-cell system. The results indicate that hydrogen diffusion coefficient increases with the increasing thickness of these membranes. Basically these alloys are all of two-phase, i.e. the primary bcc-Nb(Ni,Ti) solid solution phase and the eutectic phase of bcc-Nb(Ni,Ti)+β2-NiTi, while just a small amount of NiTi2 phase is observed in very few samples. Microstructure and composition play an important role on hydrogen diffusion. Hydrogen diffusion coefficient is increased with the increase of the content of solid solution phase; the addition of Ni and Ti lead to the variety of eutectic phase composition; the presence of NiTi phase and NiTi2 phase decreases the hydrogen diffusion coefficient, but benefits the resistance to hydrogen embrittlement induced by the crystal expansion/contraction during atomic hydrogen permeation/release. Hydrogen diffusion coefficient of Nb-Ni-Ti alloy membranes falls in the magnitude of 10-9 m2/s.
2011, 40(6):1038-1040.
Abstract:
Oxidation behavior of zirconium hydride in O2 at 450-600 °C was investigated by an isothermal oxidation experiment. The influences of temperature and oxidation time on the growth of the oxide film were studied. Results show that a parabolic law is observed in oxidation kinetics for zirconium hydride oxidation in O2 at 450-600 °C. The curves of square thickness (D2) of the oxide film with annealing time (t) follow the linear law. The oxidation progress of zirconium hydride is controlled by inward diffusion of oxygen atoms. The relationship of diffusion coefficient and temperature is represented as Arrhenius Law. The diffusion active energy of the oxidation reaction in O2 is 18724.5 J/mol, indicating a grain boundary diffusion mechanism.
Oxidation behavior of zirconium hydride in O2 at 450-600 °C was investigated by an isothermal oxidation experiment. The influences of temperature and oxidation time on the growth of the oxide film were studied. Results show that a parabolic law is observed in oxidation kinetics for zirconium hydride oxidation in O2 at 450-600 °C. The curves of square thickness (D2) of the oxide film with annealing time (t) follow the linear law. The oxidation progress of zirconium hydride is controlled by inward diffusion of oxygen atoms. The relationship of diffusion coefficient and temperature is represented as Arrhenius Law. The diffusion active energy of the oxidation reaction in O2 is 18724.5 J/mol, indicating a grain boundary diffusion mechanism.
2011, 40(6):1041-1044.
Abstract:
Prx(Co40Ag60)100-x (x=0, 0.5, 1, 1.5, 2, 3) granular films were prepared by a DC magnetron sputtering method. The XRD data indicate that Pr element can promote Co dissolving in Ag to separate from Ag and favors the (111) plane preferential orientation. Giant magnetoresistance (GMR) measurements indicate that the value of GMR increases at first and then decreases with increase of Pr content and the peak value appears at x=0.5-1.0 when the annealing temperature is below or equal to 250 oC. Proper addition of Pr to CoAg granular films can enhance GMR effect and the sensitivity to the magnetic field, whose maximum values are –14.34% and 0.67×10-3 (A/m)-1, respectively.
Prx(Co40Ag60)100-x (x=0, 0.5, 1, 1.5, 2, 3) granular films were prepared by a DC magnetron sputtering method. The XRD data indicate that Pr element can promote Co dissolving in Ag to separate from Ag and favors the (111) plane preferential orientation. Giant magnetoresistance (GMR) measurements indicate that the value of GMR increases at first and then decreases with increase of Pr content and the peak value appears at x=0.5-1.0 when the annealing temperature is below or equal to 250 oC. Proper addition of Pr to CoAg granular films can enhance GMR effect and the sensitivity to the magnetic field, whose maximum values are –14.34% and 0.67×10-3 (A/m)-1, respectively.
2011, 40(6):1045-1049.
Abstract:
The polycrystalline (SmxBa1-x)B6 (x=0.2, 0.6, 0.8) bulk cathodes were synthesized by arc plasma and spark plasma sintering (SPS). The phase, crystal structure and grain orientations of sintered bodies were investigated with XRD and EBSD, and the partial properties were tested. The results indicate that the (SmxBa1-x)B6 with high-purity prepared by SPS are random substitution solid solutions which exhibit a single phase structure. The lattice parameters increase with the increase of Ba content. The (SmxBa1-x)B6 sintered bodies with a fine grain structure have high-density and excellent mechanical properties. The (Sm0.2Ba0.8)B6 and (Sm0.8Ba0.2)B6 sintered at 60 MPa and 1400 oC for 5 min form some fiber textures which will enhance the emitting property.
The polycrystalline (SmxBa1-x)B6 (x=0.2, 0.6, 0.8) bulk cathodes were synthesized by arc plasma and spark plasma sintering (SPS). The phase, crystal structure and grain orientations of sintered bodies were investigated with XRD and EBSD, and the partial properties were tested. The results indicate that the (SmxBa1-x)B6 with high-purity prepared by SPS are random substitution solid solutions which exhibit a single phase structure. The lattice parameters increase with the increase of Ba content. The (SmxBa1-x)B6 sintered bodies with a fine grain structure have high-density and excellent mechanical properties. The (Sm0.2Ba0.8)B6 and (Sm0.8Ba0.2)B6 sintered at 60 MPa and 1400 oC for 5 min form some fiber textures which will enhance the emitting property.
2011, 40(6):1050-1054.
Abstract:
Press-infiltration technique was used to prepare Ti2AlN/TiAl composite (the Ti2AlN volume was 25%) and the high temperature oxidation behavior of Ti2AlN/TiAl was researched. The results indicate that the oxidation of the composite can be divided into two steps between 600 and 800 oC, i.e. the initial fast oxidizing and the later slow oxidizing; the oxidation are divided into three steps between 900 and 1100 oC, including the fast, slow and uniform oxidizing steps, but the second step of slow oxidizing of the composite is very short at 1100 oC. The specimens of Ti2AlN/TiAl composite were soaked at 800, 1000 and 1100 oC for 24 h, respectively, and the mass gain of them reaches 0.83, 2.58 and 27 mg/cm2, respectively. The evolution of the thickness and the structure of the oxide layer and the variety of oxides in the Ti2AlN/TiAl composite were studied at different temperatures and at different oxidation steps, and the main factors that influence the oxidation performance of the composite were discussed.
Press-infiltration technique was used to prepare Ti2AlN/TiAl composite (the Ti2AlN volume was 25%) and the high temperature oxidation behavior of Ti2AlN/TiAl was researched. The results indicate that the oxidation of the composite can be divided into two steps between 600 and 800 oC, i.e. the initial fast oxidizing and the later slow oxidizing; the oxidation are divided into three steps between 900 and 1100 oC, including the fast, slow and uniform oxidizing steps, but the second step of slow oxidizing of the composite is very short at 1100 oC. The specimens of Ti2AlN/TiAl composite were soaked at 800, 1000 and 1100 oC for 24 h, respectively, and the mass gain of them reaches 0.83, 2.58 and 27 mg/cm2, respectively. The evolution of the thickness and the structure of the oxide layer and the variety of oxides in the Ti2AlN/TiAl composite were studied at different temperatures and at different oxidation steps, and the main factors that influence the oxidation performance of the composite were discussed.
2011, 40(6):1055-1059.
Abstract:
Variation regularities of atomic interaction potentials of Ni-Al-Fe alloy based on the microscopic phase-field theory were investigated. The first nearest neighbor atomic interaction potentials of Ni-Al-Fe alloy’s L12 structure were inversed out according to the formula that illustrates the first nearest neighbor atomic interaction potentials of L12 structure alloy which was referenced on the relation equation between atomic interaction potentials and long range order parameters by Khachaturyan. The experimental results indicate that Ni-Al (WNi-Al) and Ni-Fe (WNi-Fe)’s first nearest neighbor atomic interaction potentials will increase linearly with the temperatures rising. WNi-Al increases but WNi-Fe decreases roughly linearly if Al atom’s concentration rises, and vice versa. The inversion potentials are inversed into microscopic phase-field equation, then getting a finer grain of atomic evolution pictures and a higher degree of long range order of structure.
Variation regularities of atomic interaction potentials of Ni-Al-Fe alloy based on the microscopic phase-field theory were investigated. The first nearest neighbor atomic interaction potentials of Ni-Al-Fe alloy’s L12 structure were inversed out according to the formula that illustrates the first nearest neighbor atomic interaction potentials of L12 structure alloy which was referenced on the relation equation between atomic interaction potentials and long range order parameters by Khachaturyan. The experimental results indicate that Ni-Al (WNi-Al) and Ni-Fe (WNi-Fe)’s first nearest neighbor atomic interaction potentials will increase linearly with the temperatures rising. WNi-Al increases but WNi-Fe decreases roughly linearly if Al atom’s concentration rises, and vice versa. The inversion potentials are inversed into microscopic phase-field equation, then getting a finer grain of atomic evolution pictures and a higher degree of long range order of structure.
2011, 40(6):1060-1064.
Abstract:
Mg65+x(Cu0.66Y0.34)30-xZn5 (x=5, 10, 15) alloys and their matrix composites were prepared by water-cooled copper mold casting and water quenching. The microstructures of the bulk samples were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM) in order to study the effects of Mg content and cooling rate. The results show that the alloy at x=5 prepared by water-cooled copper mold casting exhibits a fully glass structure. And the alloys at x=10 and 15 are mainly composed of the amorphous phase and Mg solid solution phase, which are amorphous composites. However, the amorphous composite materials prepared by low-cooling-rate water quenching mainly consist of Mg, Mg2Cu, MgZnY and the amorphous phase. The corrosion behavior of the alloys was studied in NaCl neutral solution. The results show that the precipitation of the crystal phase is increased with the increase of the Mg content, but at the same time the decrease of the corrosion resistance occurs. Furthermore, with the same composition, the samples prepared by water cooled copper mold casting at a high cooling rate have the best corrosion resistance while the samples prepared by water quenching at a low cooling rate have the worst.
Mg65+x(Cu0.66Y0.34)30-xZn5 (x=5, 10, 15) alloys and their matrix composites were prepared by water-cooled copper mold casting and water quenching. The microstructures of the bulk samples were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM) in order to study the effects of Mg content and cooling rate. The results show that the alloy at x=5 prepared by water-cooled copper mold casting exhibits a fully glass structure. And the alloys at x=10 and 15 are mainly composed of the amorphous phase and Mg solid solution phase, which are amorphous composites. However, the amorphous composite materials prepared by low-cooling-rate water quenching mainly consist of Mg, Mg2Cu, MgZnY and the amorphous phase. The corrosion behavior of the alloys was studied in NaCl neutral solution. The results show that the precipitation of the crystal phase is increased with the increase of the Mg content, but at the same time the decrease of the corrosion resistance occurs. Furthermore, with the same composition, the samples prepared by water cooled copper mold casting at a high cooling rate have the best corrosion resistance while the samples prepared by water quenching at a low cooling rate have the worst.
2011, 40(6):1065-1068.
Abstract:
A new method for the determination of europium by kinetic spectrophotometry was established based on the catalytic effect of europium (III) on the fading reaction of ponceau with hydrogen peroxide. The maximum absorption peak of Eu3+- H2O2-Ponceau system is located at 450 nm in a 6.0×10-2 mol/L HCl medium. The absorbance difference (△A) is linearly related with the concentration of europium (III) in the range of 0-22 μg/25 mL, fitting the equation △A = 0.0221C+0.0241 (C = μg/25 mL ), with a regression coefficient of 0.9968. Detection limit of the method is 2.42 μg/L. The method was used to determine europium in environmental water samples. The relative standard deviation was 0.49%-1.76% for 13 replicated determinations. The recovery of the standard addition of the method was 95.20%-101.3%.
A new method for the determination of europium by kinetic spectrophotometry was established based on the catalytic effect of europium (III) on the fading reaction of ponceau with hydrogen peroxide. The maximum absorption peak of Eu3+- H2O2-Ponceau system is located at 450 nm in a 6.0×10-2 mol/L HCl medium. The absorbance difference (△A) is linearly related with the concentration of europium (III) in the range of 0-22 μg/25 mL, fitting the equation △A = 0.0221C+0.0241 (C = μg/25 mL ), with a regression coefficient of 0.9968. Detection limit of the method is 2.42 μg/L. The method was used to determine europium in environmental water samples. The relative standard deviation was 0.49%-1.76% for 13 replicated determinations. The recovery of the standard addition of the method was 95.20%-101.3%.
2011, 40(6):1069-1074.
Abstract:
Vertically oriented TiO2 nanotube arrays having lengths up to 100 microns were prepares by anodic oxidation in organic electrolytes. Control of surface morphology of TiO2 nanotube arrays were surveyed principally, in order to improve the photoelectrochemical property of TiO2 nanotube array from a point of view of microstructure modification; based on these results, the photoelectrochemical properties of the nanotube arrays electrodes with different operation condition were evaluated. The results show that the surface collective block section can be removed entirely by ultrasonic cleaning in ethyl alcohol and the followed rinsing with double distilled water. The clean, regular and highly ordered nanotube arrays surface are obtained with an optimal ultrasonic duration 20-30 s. The as-prepared nanotube-array samples by single step anodic oxidation plus ultrasonic cleaning in ethyl alcohol with another 500 oC annealing show a remarkable photoconversion efficiency of 1.48% under full-spectrum illumination. It is believed that the control of surface morphology may be profitable for the improvement of the photoelectrochemical properties of TiO2 nanotube array.
Vertically oriented TiO2 nanotube arrays having lengths up to 100 microns were prepares by anodic oxidation in organic electrolytes. Control of surface morphology of TiO2 nanotube arrays were surveyed principally, in order to improve the photoelectrochemical property of TiO2 nanotube array from a point of view of microstructure modification; based on these results, the photoelectrochemical properties of the nanotube arrays electrodes with different operation condition were evaluated. The results show that the surface collective block section can be removed entirely by ultrasonic cleaning in ethyl alcohol and the followed rinsing with double distilled water. The clean, regular and highly ordered nanotube arrays surface are obtained with an optimal ultrasonic duration 20-30 s. The as-prepared nanotube-array samples by single step anodic oxidation plus ultrasonic cleaning in ethyl alcohol with another 500 oC annealing show a remarkable photoconversion efficiency of 1.48% under full-spectrum illumination. It is believed that the control of surface morphology may be profitable for the improvement of the photoelectrochemical properties of TiO2 nanotube array.
2011, 40(6):1075-1078.
Abstract:
Friction stir welding was conducted on AZ31B magnesium alloy. Variation of microstructures and properties of the welding joints before and after heat treatments was studied. The results show that post-weld heat treatments can markedly improve the mechanical properties of the friction stir-welded AZ31B magnesium alloy joints; when the rotating speed of stirring pin is 600 r·min-1 and the welding speed is 47.5 mm·min-1, the ultimate tensile strength can reach 168 MPa and the elongation is 3.6%. After heat treatments, the highest ultimate tensile strength can reach 205 MPa, which is 22.02% higher than that before heat treatments and the elongation is 8.6%, which is 138.89% higher than before heat treatments. The ideal heat treatment technique of the joint is keeping the annealing temperature at 250 oC for 1 h. As the annealing temperature increases, the growing speed of welding nugget zone grain is higher than the heat affected zone/thermo-mechanically affected zone. When the annealing temperature is higher than 250 oC, the morphologies of tensile fracture of welding joints mainly exhibit oblate dimples with a typical ductile dimple-fracture.
Friction stir welding was conducted on AZ31B magnesium alloy. Variation of microstructures and properties of the welding joints before and after heat treatments was studied. The results show that post-weld heat treatments can markedly improve the mechanical properties of the friction stir-welded AZ31B magnesium alloy joints; when the rotating speed of stirring pin is 600 r·min-1 and the welding speed is 47.5 mm·min-1, the ultimate tensile strength can reach 168 MPa and the elongation is 3.6%. After heat treatments, the highest ultimate tensile strength can reach 205 MPa, which is 22.02% higher than that before heat treatments and the elongation is 8.6%, which is 138.89% higher than before heat treatments. The ideal heat treatment technique of the joint is keeping the annealing temperature at 250 oC for 1 h. As the annealing temperature increases, the growing speed of welding nugget zone grain is higher than the heat affected zone/thermo-mechanically affected zone. When the annealing temperature is higher than 250 oC, the morphologies of tensile fracture of welding joints mainly exhibit oblate dimples with a typical ductile dimple-fracture.
2011, 40(6):1079-1083.
Abstract:
The precipitation and coarsening behavior of θ′ phase in Al-3.5Cu and Al-3.5Cu-0.5In alloys (mass fraction, %) were investigated by transmission electron microscopy (TEM), differential scanning calorimetry (DSC) and some other methods. In addition markedly accelerates the aging response of Al-Cu alloy aged at 175 oC, and raises the peak hardness by about 200 MPa. TEM observation shows that In-rich particles precipitate uniformly at the early stage of aging, which will act as heterogeneous nucleation positions of θ′ phase; In′ is observed at a corner of platelets having their broad face in the plane of view; θ′ phase is coarsened much more slowly in In-added alloy than in In-free alloy. With 6% pre-deformation before aging, these two alloys have similar aging response rate and strength, which confirms that in T6 state Indium facilitates θ′ precipitation mainly through quenched-in vacancies.
The precipitation and coarsening behavior of θ′ phase in Al-3.5Cu and Al-3.5Cu-0.5In alloys (mass fraction, %) were investigated by transmission electron microscopy (TEM), differential scanning calorimetry (DSC) and some other methods. In addition markedly accelerates the aging response of Al-Cu alloy aged at 175 oC, and raises the peak hardness by about 200 MPa. TEM observation shows that In-rich particles precipitate uniformly at the early stage of aging, which will act as heterogeneous nucleation positions of θ′ phase; In′ is observed at a corner of platelets having their broad face in the plane of view; θ′ phase is coarsened much more slowly in In-added alloy than in In-free alloy. With 6% pre-deformation before aging, these two alloys have similar aging response rate and strength, which confirms that in T6 state Indium facilitates θ′ precipitation mainly through quenched-in vacancies.
2011, 40(6):1084-1088.
Abstract:
Referring to the compositions of second phase particles (SPPs) in zirconium alloys, three kinds of experimental Zr(Fe,Cr)2 alloy with different Fe/Cr ratio i.e. Fe/Cr=2 and 0.5 for Zr(Fe,Cr)2 and Fe/Cr=0 for ZrCr2 were prepared. Then the pressure-composition- temperature (P-C-T) curves and kinetic curves of hydrogen absorbing and desorbing were obtained. XRD was employed to analyze the structures of the specimens before and after hydrogen absorbing at 360 oC. Results show that the amount of hydrogen absorption of the three alloys all increases with the decrease of Fe/Cr ratio at 50, 200 and 360 oC. In addition, the amount and rate of reversible hydrogen absorption and desorption of the three alloys all increase with the decrease of Fe/Cr ratio when tested in 360 oC, 4 MPa H2 atmosphere. X-ray diffraction analysis indicates that no hydride is detected after they absorb hydrogen at 360 oC.
Referring to the compositions of second phase particles (SPPs) in zirconium alloys, three kinds of experimental Zr(Fe,Cr)2 alloy with different Fe/Cr ratio i.e. Fe/Cr=2 and 0.5 for Zr(Fe,Cr)2 and Fe/Cr=0 for ZrCr2 were prepared. Then the pressure-composition- temperature (P-C-T) curves and kinetic curves of hydrogen absorbing and desorbing were obtained. XRD was employed to analyze the structures of the specimens before and after hydrogen absorbing at 360 oC. Results show that the amount of hydrogen absorption of the three alloys all increases with the decrease of Fe/Cr ratio at 50, 200 and 360 oC. In addition, the amount and rate of reversible hydrogen absorption and desorption of the three alloys all increase with the decrease of Fe/Cr ratio when tested in 360 oC, 4 MPa H2 atmosphere. X-ray diffraction analysis indicates that no hydride is detected after they absorb hydrogen at 360 oC.
2011, 40(6):1089-1092.
Abstract:
The VO2(A) thin films with the property of the thermochromic phase transition were prepared by vacuum evaporation deoxidization technology with the V2O5 powders (purity≥99.99%) as starting materials. The morphology of the VO2(A) thin films were studied, which were affected by the annealing temperature, and its effects on the optical properties and electrical properties were also studied. The results show that the stratiform characteristics are weakened until disappear and the peak-like particles appear and become large when the annealing temperature increases from 500 oC to 540 oC; however, the peak particles diminish firstly and then become large when the annealing temperature continues to increase, but the sizes of the particles become similar, about 50 nm. With the alteration of the morphology, the parameters of the phase transition, such as the critical temperature, the order of magnitude and the hysteresis loop width will change correspondingly. As the critical temperature decreases, the transmission of the thin films will decrease correspondingly, but only the transmission in the middle infrared during the phase transition changes correspondingly to the order of magnitude.
The VO2(A) thin films with the property of the thermochromic phase transition were prepared by vacuum evaporation deoxidization technology with the V2O5 powders (purity≥99.99%) as starting materials. The morphology of the VO2(A) thin films were studied, which were affected by the annealing temperature, and its effects on the optical properties and electrical properties were also studied. The results show that the stratiform characteristics are weakened until disappear and the peak-like particles appear and become large when the annealing temperature increases from 500 oC to 540 oC; however, the peak particles diminish firstly and then become large when the annealing temperature continues to increase, but the sizes of the particles become similar, about 50 nm. With the alteration of the morphology, the parameters of the phase transition, such as the critical temperature, the order of magnitude and the hysteresis loop width will change correspondingly. As the critical temperature decreases, the transmission of the thin films will decrease correspondingly, but only the transmission in the middle infrared during the phase transition changes correspondingly to the order of magnitude.
33 Vibration Fatigue Performance Improvement of K417 Alloy by Laser Shock Processing and Aluminizing
2011, 40(6):1093-1096.
Abstract:
The feasibility of improving the vibration fatigue performance of K417 alloy by laser shock processing and aluminizing was studied. The result shows that the vibration fatigue performance of K417 alloy is effectively enhanced by laser shock processing and aluminizing. The specimens were analyzed by SEM and TEM, and the mechanism of the vibration fatigue performance improvement was discussed.
The feasibility of improving the vibration fatigue performance of K417 alloy by laser shock processing and aluminizing was studied. The result shows that the vibration fatigue performance of K417 alloy is effectively enhanced by laser shock processing and aluminizing. The specimens were analyzed by SEM and TEM, and the mechanism of the vibration fatigue performance improvement was discussed.
2011, 40(6):1097-1011.
Abstract:
The microstructure, surface morphology, and magnetic properties of the sintered NdFeB permanent magnet prepared by the HDDR method were analyzed by X-ray diffraction, scanning electron microscopy and BH magnetic measurement. Microstructural studies show that NdFeB magnets which were firstly prepared by HDDR powder and then sintered at the high-temperature of 1080 oC consist of a large amount of the tetragonal phase Nd2Fe14B (P42/mnm) and trace amount of rare earth-rich phase. SEM images indicate that the average grain size of the Nd2Fe14B phase is about 12.3 μm. The density factor of (006) crystal face of Nd2Fe14B phase is estimated as about 3.5 using Horta formula, suggesting that the sample has a strong c-axis orientation. The demagnetic curves at different temperatures show that at room temperature this sample has well magnetic properties, i.e. (BH)max 264 kJ/m3, remanence Br about 1.17 T, and coercive Hcj 2038 kA/m. With the temperature increasing, magnetic properties of the samples are monotonicly reduced, especially for the coercivity which is reduced by 1496 kA/m from 295 to 448 K. The coercivity mechanism of the NdFeB magnets prepared by HDDR method was analyzed by studying the behavior of Hc(T)/Ms(T) versus (T)/Ms(T) (Kronmüller-plot). The results of Kronmüller-plot show that nucleation is the dominating mechanism for the magnetization reversal in these samples. Micromagnetic parameters αk of 1.39 and Neff of 1.75 are responsible for the high coercivity of magnetic alloys.
The microstructure, surface morphology, and magnetic properties of the sintered NdFeB permanent magnet prepared by the HDDR method were analyzed by X-ray diffraction, scanning electron microscopy and BH magnetic measurement. Microstructural studies show that NdFeB magnets which were firstly prepared by HDDR powder and then sintered at the high-temperature of 1080 oC consist of a large amount of the tetragonal phase Nd2Fe14B (P42/mnm) and trace amount of rare earth-rich phase. SEM images indicate that the average grain size of the Nd2Fe14B phase is about 12.3 μm. The density factor of (006) crystal face of Nd2Fe14B phase is estimated as about 3.5 using Horta formula, suggesting that the sample has a strong c-axis orientation. The demagnetic curves at different temperatures show that at room temperature this sample has well magnetic properties, i.e. (BH)max 264 kJ/m3, remanence Br about 1.17 T, and coercive Hcj 2038 kA/m. With the temperature increasing, magnetic properties of the samples are monotonicly reduced, especially for the coercivity which is reduced by 1496 kA/m from 295 to 448 K. The coercivity mechanism of the NdFeB magnets prepared by HDDR method was analyzed by studying the behavior of Hc(T)/Ms(T) versus (T)/Ms(T) (Kronmüller-plot). The results of Kronmüller-plot show that nucleation is the dominating mechanism for the magnetization reversal in these samples. Micromagnetic parameters αk of 1.39 and Neff of 1.75 are responsible for the high coercivity of magnetic alloys.
2011, 40(6):1102-1104.
Abstract:
钼；铼；分离；双水相
钼；铼；分离；双水相
Wang Boyu
,
Xiang Wei
,
Dai Jingyi
,
Tan Xiaohua
,
Cheng Liang
,
Chen Lei
,
Xu Jinzhang
,
Chen Ximeng
,
Yao Ze’en
,
Guo Zhiqiang
2011, 40(6):1105-1109.
Abstract:
Interaction of the deuterium ion beam and the drive-in titanium target was studied by measuring the neutron yield as a function of bombarding time with the associated particles method in ZF-300 neutron generation. X-ray diffraction for phase analyses and scanning electron microscopy for the surface morphology were used to characterize the targets. During the bombarding period with deuterium ion beam, the neutron yield increases gradually with deuterium ion beam implantment at first, and then it decreases slowly. There is no obvious melting crater on the surface of the titanium targets bombarded with deuterium ion beam. With the increase of deuterium ion beam intensity, the transverse polishing marks of the titanium targets disappear gradually. The phase of the drive-in titanium target is not changed in the experiment conditions. The prominent physical mechanism of the deuterium ion beam and the drive-in titanium target interaction was discussed based on the numerical simulation of the beam and the solid interaction.
Interaction of the deuterium ion beam and the drive-in titanium target was studied by measuring the neutron yield as a function of bombarding time with the associated particles method in ZF-300 neutron generation. X-ray diffraction for phase analyses and scanning electron microscopy for the surface morphology were used to characterize the targets. During the bombarding period with deuterium ion beam, the neutron yield increases gradually with deuterium ion beam implantment at first, and then it decreases slowly. There is no obvious melting crater on the surface of the titanium targets bombarded with deuterium ion beam. With the increase of deuterium ion beam intensity, the transverse polishing marks of the titanium targets disappear gradually. The phase of the drive-in titanium target is not changed in the experiment conditions. The prominent physical mechanism of the deuterium ion beam and the drive-in titanium target interaction was discussed based on the numerical simulation of the beam and the solid interaction.
2011, 40(6):1110-1114.
Abstract:
A coating was prepared on zirconium by micro-arc oxidation. The effects of voltage, frequency, duty-cycle and current density on the thickness of the MAO coating were studied, and the significances of the effects were also studied by ANOVA. The results show that the thickness of the coating increases with the voltage, duty-cycle and current density increasing and the frequency decreasing separately, the primary-secondary order of the effect significances for all parameters is voltage and current density > duty-cycle > frequency, and the frequency has little effect on the coating thickness.
A coating was prepared on zirconium by micro-arc oxidation. The effects of voltage, frequency, duty-cycle and current density on the thickness of the MAO coating were studied, and the significances of the effects were also studied by ANOVA. The results show that the thickness of the coating increases with the voltage, duty-cycle and current density increasing and the frequency decreasing separately, the primary-secondary order of the effect significances for all parameters is voltage and current density > duty-cycle > frequency, and the frequency has little effect on the coating thickness.
2011, 40(6):1115-1119.
Abstract:
The effects of melting time, crucible diameter and ingot mass on chemical homogeneity and the content of carbon and oxygen impurity in TiNi alloy were studied by vacuum induction melting in graphite crucible. The results show that the impurity content is increased with an increase in melting time and A/V ratio, and the effect extent on carbon content is much greater than that on oxygen. The A/V ratio has a close relationship with the crucible diameter and ingot mass under the coordinative condition. The 10-20 kg ingot with few impurity and excellent homogeneity can be obtained by adopting 10 min+15 min melting time plus 160 mm diameter crucible.
The effects of melting time, crucible diameter and ingot mass on chemical homogeneity and the content of carbon and oxygen impurity in TiNi alloy were studied by vacuum induction melting in graphite crucible. The results show that the impurity content is increased with an increase in melting time and A/V ratio, and the effect extent on carbon content is much greater than that on oxygen. The A/V ratio has a close relationship with the crucible diameter and ingot mass under the coordinative condition. The 10-20 kg ingot with few impurity and excellent homogeneity can be obtained by adopting 10 min+15 min melting time plus 160 mm diameter crucible.
2011, 40(6):1120-1124.
Abstract:
A new three-step method for preparing aluminum rich coating on HR-2 stainless steel was proposed, i.e. ambient temperature chloroaluminate melts electroplating followed by heat treating and artificial oxidation. In the electroplating process, aluminum deposition from AlCl3/MEIC to the surface of HR-2 steel was performed with a deposition rate of 15 μm/h. Within the aluminizing temperature range from 650 to 750 oC, aluminizing time from 1 to 30 h, the aluminized coating with thickness of 3-27 μm can be prepared, which is homogeneous and free of porosity or crack, and have good metallographic adherence to the substrate; the coating cross section exhibits a three-layer or two-layer structure. A simple Arrhenius relationship can be used to describe the effect of temperature on the coating growth rate, which gives activation energy of 116.9 kJ/mol. The relationship between the coating thickness against time1/2 is approximately linear, which is a typical feature of the diffusion controlled coating growth mechanism. To form Al2O3 film on surface, the aluminized coating treated for 4 h was oxidized in 10-2 Pa O2 for 80 h and observed by X-ray photoelectron spectroscopy (XPS) and Reflection spectrum. The finally fabricated coating shows a double-layer structure consisting of an outer γ-A12O3 layer with thickness of 110 nm and inner (Fe,Cr,Mn and Ni)Al/(Fe,Cr,Mn and Ni)3Al layer of 30 μm thickness, and is homogeneous without any defects. The deuterium permeation rate through the coated HR-2 steel is reduced by 3 orders of magnitude at 600 oC. The coating remains a perfect surface for 20 thermal cycles between 750 oC and room temperature. The method is a potential candidate for preparation of TPB on the tritium container surface in ITER.
A new three-step method for preparing aluminum rich coating on HR-2 stainless steel was proposed, i.e. ambient temperature chloroaluminate melts electroplating followed by heat treating and artificial oxidation. In the electroplating process, aluminum deposition from AlCl3/MEIC to the surface of HR-2 steel was performed with a deposition rate of 15 μm/h. Within the aluminizing temperature range from 650 to 750 oC, aluminizing time from 1 to 30 h, the aluminized coating with thickness of 3-27 μm can be prepared, which is homogeneous and free of porosity or crack, and have good metallographic adherence to the substrate; the coating cross section exhibits a three-layer or two-layer structure. A simple Arrhenius relationship can be used to describe the effect of temperature on the coating growth rate, which gives activation energy of 116.9 kJ/mol. The relationship between the coating thickness against time1/2 is approximately linear, which is a typical feature of the diffusion controlled coating growth mechanism. To form Al2O3 film on surface, the aluminized coating treated for 4 h was oxidized in 10-2 Pa O2 for 80 h and observed by X-ray photoelectron spectroscopy (XPS) and Reflection spectrum. The finally fabricated coating shows a double-layer structure consisting of an outer γ-A12O3 layer with thickness of 110 nm and inner (Fe,Cr,Mn and Ni)Al/(Fe,Cr,Mn and Ni)3Al layer of 30 μm thickness, and is homogeneous without any defects. The deuterium permeation rate through the coated HR-2 steel is reduced by 3 orders of magnitude at 600 oC. The coating remains a perfect surface for 20 thermal cycles between 750 oC and room temperature. The method is a potential candidate for preparation of TPB on the tritium container surface in ITER.
2011, 40(6):1125-1128.
Abstract:
A mini-spherical model of fuel was designed and the irradiation swelling of U10Mo-Al dispersion fuel was simulated by the model. The results show that a higher irradiation temperature leads to a more obvious swelling of fuel. With the fission rate increasing, below the turning point of burnup the rate of swelling is nearly the same; however, beyond the turning point of burnup, the rate of swelling is slower at higher fission rate. The predicted results are well consistent with the experimental in a reasonable range.
A mini-spherical model of fuel was designed and the irradiation swelling of U10Mo-Al dispersion fuel was simulated by the model. The results show that a higher irradiation temperature leads to a more obvious swelling of fuel. With the fission rate increasing, below the turning point of burnup the rate of swelling is nearly the same; however, beyond the turning point of burnup, the rate of swelling is slower at higher fission rate. The predicted results are well consistent with the experimental in a reasonable range.
