Volume 44,Issue 3,2015 Table of Contents
2015, 44(3):527-531.
Abstract:
It is critical to reveal the evolution rules of two types of α platelets (secondary lamellar α and thin α lath in transformed β matrix) in the tri-modal microstructure of TA15 alloy so as to obtain exceptional properties through microstructural design. The combined effects of isothermal compression (at 950, 965, and 975 °C) and subsequent double heat treatments (a high-temperature heat treatment at 10 °C to 40 °C below the compression temperature followed by a 810 °C heat treatment) on the evolution of the two types of α platelets were studied. The results show that the isolated lamellar α and the thin α lath can be produced by first heat treatment at 10 °C below the compression temperature and the thin α lath in this structure has a colony morphology under air cooling and an acicular morphology under water quenching. Colony and basketweave lamellar α and thin α lath can be produced when the first heat treatment is at 25 °C below the compression temperature. Only the colony and basketweave lamellar α can be produced when the first heat treatment temperature is 40 °C lower than the compression temperature. Besides, the morphology of lamellar α is not substantially influenced by cooling modes after the first heat treatment at the same temperatures.
It is critical to reveal the evolution rules of two types of α platelets (secondary lamellar α and thin α lath in transformed β matrix) in the tri-modal microstructure of TA15 alloy so as to obtain exceptional properties through microstructural design. The combined effects of isothermal compression (at 950, 965, and 975 °C) and subsequent double heat treatments (a high-temperature heat treatment at 10 °C to 40 °C below the compression temperature followed by a 810 °C heat treatment) on the evolution of the two types of α platelets were studied. The results show that the isolated lamellar α and the thin α lath can be produced by first heat treatment at 10 °C below the compression temperature and the thin α lath in this structure has a colony morphology under air cooling and an acicular morphology under water quenching. Colony and basketweave lamellar α and thin α lath can be produced when the first heat treatment is at 25 °C below the compression temperature. Only the colony and basketweave lamellar α can be produced when the first heat treatment temperature is 40 °C lower than the compression temperature. Besides, the morphology of lamellar α is not substantially influenced by cooling modes after the first heat treatment at the same temperatures.
2015, 44(3):532-537.
Abstract:
The incompatibility of plastic deformation in a near β titanium alloy with (α + β) two phases microstructure was analyzed based on the crystal plasticity finite element (CPFE) model. The bicrystal simulation results show that the plastic deformation in the (α + β) two phases microstructure is incompatible, and the deformation behavior of α phase is significantly affected by the crystal orientation and loading direction. In addition, through coupling with three-dimensional (3D) Voronoi tessellation (VT) geometric model, the effect of globular primary α phase in the β matrix on the macroscopic mechanical response was discussed. Based on the CPFE-VT model, it is found that the incompatibility of plastic deformation between the α and β phases can result in a linear reduction of the macroscopic strength with the increase of the volume fraction of α phase. Furthermore, the distribution of primary α phase also plays an important role in the stress-strain response. The proposed model for near β titanium alloy can yield important informations for the microstructure controlling and the performance prediction.
The incompatibility of plastic deformation in a near β titanium alloy with (α + β) two phases microstructure was analyzed based on the crystal plasticity finite element (CPFE) model. The bicrystal simulation results show that the plastic deformation in the (α + β) two phases microstructure is incompatible, and the deformation behavior of α phase is significantly affected by the crystal orientation and loading direction. In addition, through coupling with three-dimensional (3D) Voronoi tessellation (VT) geometric model, the effect of globular primary α phase in the β matrix on the macroscopic mechanical response was discussed. Based on the CPFE-VT model, it is found that the incompatibility of plastic deformation between the α and β phases can result in a linear reduction of the macroscopic strength with the increase of the volume fraction of α phase. Furthermore, the distribution of primary α phase also plays an important role in the stress-strain response. The proposed model for near β titanium alloy can yield important informations for the microstructure controlling and the performance prediction.
2015, 44(3):538-543.
Abstract:
The amorphous Ni-Mo-W alloy coating with high HER (hydrogen evolution reaction) activity was obtained by pulse plating. In view of HER overpotential, the optimum electrodeposition conditions to prepare Ni-Mo-W coating in pulse plating process were determined, e.g. Na2WO4·2H2O concentration, average current density and duty cycle. Correspondingly, the effects of molybdenum and the tungsten contents on the compositions and the components of Ni-Mo-W coatings were investigated systematically. The results show that adding tungsten into Ni-Mo binary alloy coating could increase the HER activity effectively (h200 = 80 mV) and the amorphous microstructure of Ni-Mo-W coating mainly depends on the molybdenum content. After long-term electrolysis, compared with amorphous Ni-Mo coating, the electrochemical stability of amorphous Ni-Mo-W coating is improved to some extent due to the poor dissolution of molybdenum and tungsten.
The amorphous Ni-Mo-W alloy coating with high HER (hydrogen evolution reaction) activity was obtained by pulse plating. In view of HER overpotential, the optimum electrodeposition conditions to prepare Ni-Mo-W coating in pulse plating process were determined, e.g. Na2WO4·2H2O concentration, average current density and duty cycle. Correspondingly, the effects of molybdenum and the tungsten contents on the compositions and the components of Ni-Mo-W coatings were investigated systematically. The results show that adding tungsten into Ni-Mo binary alloy coating could increase the HER activity effectively (h200 = 80 mV) and the amorphous microstructure of Ni-Mo-W coating mainly depends on the molybdenum content. After long-term electrolysis, compared with amorphous Ni-Mo coating, the electrochemical stability of amorphous Ni-Mo-W coating is improved to some extent due to the poor dissolution of molybdenum and tungsten.
2015, 44(3):548-552.
Abstract:
Aluminum Foam Sandwich (AFS) panels consist of a highly porous aluminum foam core and metal face sheets. They have been known as a new functional material with many excellent comprehensive properties. AFS panels not only have many excellent properties of aluminum foam materials (extremely low density, efficient capacity of energy dissipation, high specific strength and specific stiffness, acoustic and thermal insulation, high damping, etc.), but also solve the shortcoming of low strength of single aluminum foams, which makes them interesting for a number of practical applications, such as the realization of lightweight structures with a high mechanical strength and a good capacity of energy dissipation under impacts. So far, they have received a considerable attention from?a?great number of?researchers. In this work, the development of the preparation method of AFS panels was reviewed, and the merits and faults of different processes were discussed.
Aluminum Foam Sandwich (AFS) panels consist of a highly porous aluminum foam core and metal face sheets. They have been known as a new functional material with many excellent comprehensive properties. AFS panels not only have many excellent properties of aluminum foam materials (extremely low density, efficient capacity of energy dissipation, high specific strength and specific stiffness, acoustic and thermal insulation, high damping, etc.), but also solve the shortcoming of low strength of single aluminum foams, which makes them interesting for a number of practical applications, such as the realization of lightweight structures with a high mechanical strength and a good capacity of energy dissipation under impacts. So far, they have received a considerable attention from?a?great number of?researchers. In this work, the development of the preparation method of AFS panels was reviewed, and the merits and faults of different processes were discussed.
2015, 44(3):557-562.
Abstract:
The tribological behavior and wear mechanism of a Mo-alloyed layer prepared by a double-glow plasma surface alloying technique were investigated under different loads. The microstructure, the composition distribution and the phase structure of the Mo-alloyed layer were characterized by SEM, EDS and XRD, respectively. The results show that the uniform and compact Mo-alloyed layer with 20 μm thickness is composed of phases Mo, Al3Ti and Al8(Ti3-xMox). The sliding wear experiments were performed under different loads (1.3, 5.3 and 9.3 N) in order to examine the tribological properties of the Mo-alloyed layer. The average friction coefficients and the wear rates of Mo-alloyed layer both show an upward tendency with the increased of loads. Mild abrasion wear and oxidative wear could be detected under 1.3 N load based on the analysis results of 3D surface morphologies, SEM and EDS. The wear mechanism under 5.3 N load is dominated by oxidative wear and abrasion wear. Oxidative wear, abrasion wear and adhesive wear are the main wear mechanism under 9.3 N.
The tribological behavior and wear mechanism of a Mo-alloyed layer prepared by a double-glow plasma surface alloying technique were investigated under different loads. The microstructure, the composition distribution and the phase structure of the Mo-alloyed layer were characterized by SEM, EDS and XRD, respectively. The results show that the uniform and compact Mo-alloyed layer with 20 μm thickness is composed of phases Mo, Al3Ti and Al8(Ti3-xMox). The sliding wear experiments were performed under different loads (1.3, 5.3 and 9.3 N) in order to examine the tribological properties of the Mo-alloyed layer. The average friction coefficients and the wear rates of Mo-alloyed layer both show an upward tendency with the increased of loads. Mild abrasion wear and oxidative wear could be detected under 1.3 N load based on the analysis results of 3D surface morphologies, SEM and EDS. The wear mechanism under 5.3 N load is dominated by oxidative wear and abrasion wear. Oxidative wear, abrasion wear and adhesive wear are the main wear mechanism under 9.3 N.
2015, 44(3):567-570.
Abstract:
The paper investigated grain sizes and cracks between the edge and the center of Cu-Cr-Zr alloy bar through macrostructure and microstructure. A crack in the center was explored by images of transverse and longitudinal sections with scanning electron microscope (SEM). Results show that the grain size in the edge is obviously finer than that in the center as completely dynamic recrystallization occurs easily; the microcrack of about 40 μm is formed in the center by second phase particles. Some bcc type precipitates Cr and intermetallics such as Cu51Zr14 and Cu5Zr are the source of microcracks initiation owing to coarse grains decreasing the strength. Therefore, refining of grains in the center is necessary to prevent microcracks. The formation mechanism of cracks can be explained by a dislocation model of microporosity nucleating, growing and polymerizing (MNGP).
The paper investigated grain sizes and cracks between the edge and the center of Cu-Cr-Zr alloy bar through macrostructure and microstructure. A crack in the center was explored by images of transverse and longitudinal sections with scanning electron microscope (SEM). Results show that the grain size in the edge is obviously finer than that in the center as completely dynamic recrystallization occurs easily; the microcrack of about 40 μm is formed in the center by second phase particles. Some bcc type precipitates Cr and intermetallics such as Cu51Zr14 and Cu5Zr are the source of microcracks initiation owing to coarse grains decreasing the strength. Therefore, refining of grains in the center is necessary to prevent microcracks. The formation mechanism of cracks can be explained by a dislocation model of microporosity nucleating, growing and polymerizing (MNGP).
2015, 44(3):576-580.
Abstract:
A hypoeutectic Al-Si matrix composite reinforced by 5wt% Mg2Si was prepared under different superheats and electromagnetic stirring (EMS), and the effects of pouring temperature (superheat) and EMS on the morphology and the grain size distribution of primary α-Al, (α-Al+Mg2Si) eutectic cell and eutectic Mg2Si were investigated. The results show that the low superheat + EMS process refines the grain structure of the primary α-Al and (α-Al+Mg2Si) eutectic cell, promotes the formation of more non-dendritic structure of the phases, as well as refines the eutectic Mg2Si and changes the nucleation mode of (α-Al+Mg2Si) binary eutectic from the nucleation on primary α-Al under conventional casting to the one on nucleant particles in the interdendritic liquid under low superheat + EMS.
A hypoeutectic Al-Si matrix composite reinforced by 5wt% Mg2Si was prepared under different superheats and electromagnetic stirring (EMS), and the effects of pouring temperature (superheat) and EMS on the morphology and the grain size distribution of primary α-Al, (α-Al+Mg2Si) eutectic cell and eutectic Mg2Si were investigated. The results show that the low superheat + EMS process refines the grain structure of the primary α-Al and (α-Al+Mg2Si) eutectic cell, promotes the formation of more non-dendritic structure of the phases, as well as refines the eutectic Mg2Si and changes the nucleation mode of (α-Al+Mg2Si) binary eutectic from the nucleation on primary α-Al under conventional casting to the one on nucleant particles in the interdendritic liquid under low superheat + EMS.
2015, 44(3):581-586.
Abstract:
Many microstructural defects such as well-developed dendritic crystal and severe segregation have been found in 7075 aluminum alloy strips by continuous twin-roll casters. Morphology and phase composition of 7075 alloy strips were tested in this paper. Electromagnetic field of 0.13 T was applied during a twin-roll casting (TRC) process to study the difference in solute element distribution compared to conventional process. The most soundest method by which the microstructure of slabs was greatly refined and equiaxed, and segregation bands narrowed down efficiently, was an alternating oscillating process with industrial frequency current and frequency of 386 A and 50 Hz, respectively. In addition, t (AlZnMgCu) phase with high density was formed at (sub) grain boundaries, which was refined and homogenized consecutively in accordance with direct chill (DC) electromagnetic field, half-wave oscillating field and alternating oscillating field; moreover, netlike precipitates completely disappeared at oscillating TRC processes.
Many microstructural defects such as well-developed dendritic crystal and severe segregation have been found in 7075 aluminum alloy strips by continuous twin-roll casters. Morphology and phase composition of 7075 alloy strips were tested in this paper. Electromagnetic field of 0.13 T was applied during a twin-roll casting (TRC) process to study the difference in solute element distribution compared to conventional process. The most soundest method by which the microstructure of slabs was greatly refined and equiaxed, and segregation bands narrowed down efficiently, was an alternating oscillating process with industrial frequency current and frequency of 386 A and 50 Hz, respectively. In addition, t (AlZnMgCu) phase with high density was formed at (sub) grain boundaries, which was refined and homogenized consecutively in accordance with direct chill (DC) electromagnetic field, half-wave oscillating field and alternating oscillating field; moreover, netlike precipitates completely disappeared at oscillating TRC processes.
2015, 44(3):587-591.
Abstract:
Al5052/Mg-9.5Li-2Al alloy clad plates were fabricated by cold rolling and the effect of annealing temperature on the microstructures and mechanical properties were investigated. Results show that no defects like cracks or voids are found at the bond interface in the annealed clad plates. Intermetallic layers are formed at the clad plate bond interface after annealing at and above 623 K. The main phases across the bond interface are α-Mg+b-Li, Mg17Al12, Li-dissolved Al3Mg2 and α-Al in sequence from the Mg-9.5Li-2Al base plate to Al5052 cover plate. The bond strength increases with increasing of annealing temperature below 623 K. When annealed at 623 K, the interfacial normal bond strength of the clad plates attains its maximum 17.83 MPa, with excellent ductility of an elongation of 18.7%, and no debonding is observed in the tensile specimen. When annealed at 673 K, the tensile property of the clad plates worsens due to interface debonding.
Al5052/Mg-9.5Li-2Al alloy clad plates were fabricated by cold rolling and the effect of annealing temperature on the microstructures and mechanical properties were investigated. Results show that no defects like cracks or voids are found at the bond interface in the annealed clad plates. Intermetallic layers are formed at the clad plate bond interface after annealing at and above 623 K. The main phases across the bond interface are α-Mg+b-Li, Mg17Al12, Li-dissolved Al3Mg2 and α-Al in sequence from the Mg-9.5Li-2Al base plate to Al5052 cover plate. The bond strength increases with increasing of annealing temperature below 623 K. When annealed at 623 K, the interfacial normal bond strength of the clad plates attains its maximum 17.83 MPa, with excellent ductility of an elongation of 18.7%, and no debonding is observed in the tensile specimen. When annealed at 673 K, the tensile property of the clad plates worsens due to interface debonding.
2015, 44(3):603-607.
Abstract:
Thermal stress and optimum structure design of tungsten/copper functional gradient materials (W/Cu FGM) were analyzed via ANSYS12.0 code. The results show that the maximum thermal stresses firstly decrease to a bottom value and then slightly increase with the increasing of compositional exponent (p) of W/Cu FGM. The equivalent Von Mises thermal stress for the W/Cu FGM (p=1.3) is 180 MPa, decreased by 79% compared with non-FGM under heat flux of 30 MW/m2. According to the simulation results, the optimal parameters of the W/Cu FGM are listed as following: above 3 mm for the thickness, 4~6 layer for the W/Cu FGM and 1 mm to 3 mm of the thickness for the tungsten layer.
Thermal stress and optimum structure design of tungsten/copper functional gradient materials (W/Cu FGM) were analyzed via ANSYS12.0 code. The results show that the maximum thermal stresses firstly decrease to a bottom value and then slightly increase with the increasing of compositional exponent (p) of W/Cu FGM. The equivalent Von Mises thermal stress for the W/Cu FGM (p=1.3) is 180 MPa, decreased by 79% compared with non-FGM under heat flux of 30 MW/m2. According to the simulation results, the optimal parameters of the W/Cu FGM are listed as following: above 3 mm for the thickness, 4~6 layer for the W/Cu FGM and 1 mm to 3 mm of the thickness for the tungsten layer.
11 Thermal Property, Structure and Magnetic Property of (Fe1-xCox)80Zr10B10 (x=0, 0.1, 0.2, 0.3) Alloys
2015, 44(3):616-620.
Abstract:
(Fe1-xCox)80Zr10B10 (x=0, 0.1, 0.2, 0.3) amorphous ribbons were prepared by the single roller melt-spinning and they are isothermally annealed at different temperatures. Thermal properties, microstructures and magnetic properties of the samples were investigated by differential thermal analysis (DTA), X-ray diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The results show that the thermal stability of the Co-free alloy is higher than that of the Co-containing alloys. However, there is little difference in the thermal stability of (Fe1-xCox)80Zr10B10 (x=0.1, 0.2, 0.3) alloys. The crystallization processes of Fe80Zr10B10 and Fe72Co8Zr10B10 alloys are similar. The crystallization processes of Fe64Co16Zr10B10 and Fe56Co24Zr10B10 alloys are similar. Coercivity (Hc) of the four alloys all increase firstly and then decrease. At 873 K, Hc all reaches the maximum.
(Fe1-xCox)80Zr10B10 (x=0, 0.1, 0.2, 0.3) amorphous ribbons were prepared by the single roller melt-spinning and they are isothermally annealed at different temperatures. Thermal properties, microstructures and magnetic properties of the samples were investigated by differential thermal analysis (DTA), X-ray diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The results show that the thermal stability of the Co-free alloy is higher than that of the Co-containing alloys. However, there is little difference in the thermal stability of (Fe1-xCox)80Zr10B10 (x=0.1, 0.2, 0.3) alloys. The crystallization processes of Fe80Zr10B10 and Fe72Co8Zr10B10 alloys are similar. The crystallization processes of Fe64Co16Zr10B10 and Fe56Co24Zr10B10 alloys are similar. Coercivity (Hc) of the four alloys all increase firstly and then decrease. At 873 K, Hc all reaches the maximum.
2015, 44(3):634-637.
Abstract:
Bulk amorphous (Nd0.7Pr0.3)60-xFe30Al10Cux (x=0, 1, 2 , 4) alloys with diameter of 2 mm were prepared by argon arc melting and suction casting the molten alloy into a copper mould. The magnetic properties and coercivity mechanism of the alloys were investigated by the measurement of major hysteresis loop, exchange coupling curve (dM-H plot), magnetic viscosity and the temperature dependence of the coercivity. At room temperature, all the alloys exhibit hard magnetic properties. The coercivity increases slightly with increasing the Cu content, while the remanence has the same values. The fluctuation field, Hf, is determined from sweep rate measurement. It is in the range of 12.1~15.2 mT. The thermal activation volume, va, is from 1.5×10-18 to 1.9×10-18 cm3. The exchange coupling interaction in all four alloys is confirmed by the dM-H plot. The temperature dependence of the coercivity can be well explained by Gaunt’s strong pinning model of domain walls. The hard magnetic behavior of bulk amorphous (Nd0.7Pr0.3)60-xFe30Al10Cux (x=0, 1, 2, 4) alloys may be determined by the exchange coupling interaction among clusters and strong domain wall pinning.
Bulk amorphous (Nd0.7Pr0.3)60-xFe30Al10Cux (x=0, 1, 2 , 4) alloys with diameter of 2 mm were prepared by argon arc melting and suction casting the molten alloy into a copper mould. The magnetic properties and coercivity mechanism of the alloys were investigated by the measurement of major hysteresis loop, exchange coupling curve (dM-H plot), magnetic viscosity and the temperature dependence of the coercivity. At room temperature, all the alloys exhibit hard magnetic properties. The coercivity increases slightly with increasing the Cu content, while the remanence has the same values. The fluctuation field, Hf, is determined from sweep rate measurement. It is in the range of 12.1~15.2 mT. The thermal activation volume, va, is from 1.5×10-18 to 1.9×10-18 cm3. The exchange coupling interaction in all four alloys is confirmed by the dM-H plot. The temperature dependence of the coercivity can be well explained by Gaunt’s strong pinning model of domain walls. The hard magnetic behavior of bulk amorphous (Nd0.7Pr0.3)60-xFe30Al10Cux (x=0, 1, 2, 4) alloys may be determined by the exchange coupling interaction among clusters and strong domain wall pinning.
2015, 44(3):649-655.
Abstract:
It is very important to study and master the rule of incremental forming of magnesium alloys under different process parameters for theoretical and practical application. Therefore, the effects of different possessing parameters including the forming temperature, friction condition and the tool head diameter on the hot single point incremental forming of AZ31B magnesium alloys were studied using the variable angle cone piece as the research object, and the parts’ effective stress, as well as the max thickness reduction ratio and thickness changes as research target by the finite element software ANSYS/LS-DYNA. The results show that the AZ31B magnesium alloy exhibits good single point incremental forming ability when the forming temperature is 250 oC, the static friction coefficient 0.2, the kinetic friction coefficient 0.1 and the tool head diameter in the range of 10~12 mm.
It is very important to study and master the rule of incremental forming of magnesium alloys under different process parameters for theoretical and practical application. Therefore, the effects of different possessing parameters including the forming temperature, friction condition and the tool head diameter on the hot single point incremental forming of AZ31B magnesium alloys were studied using the variable angle cone piece as the research object, and the parts’ effective stress, as well as the max thickness reduction ratio and thickness changes as research target by the finite element software ANSYS/LS-DYNA. The results show that the AZ31B magnesium alloy exhibits good single point incremental forming ability when the forming temperature is 250 oC, the static friction coefficient 0.2, the kinetic friction coefficient 0.1 and the tool head diameter in the range of 10~12 mm.
2015, 44(3):656-659.
Abstract:
The effects of thickness and temperature on the in-plane thermal conductivities of germanium single-crystal thin films have been investigated by a non-equilibrium molecular dynamics (NEMD) simulation method. The Stillinger-Weber potential model was employed to describe the interaction between atoms in the germanium single-crystal thin films. Taking structural characteristics and heat transfer mechanism of the germanium single-crystal thin films, a steady heat transfer model was framed. The results of calculations demonstrate that the in-plane thermal conductivities of germanium single-crystal thin films show an obvious size effect, which increases with increasing of thin film thickness and decreases with increasing of temperature. Comparing with the cross-plane thermal conductivity, the simulation results prove that the thermal conductivities of germanium single-crystal thin films have anisotropic characteristics.
The effects of thickness and temperature on the in-plane thermal conductivities of germanium single-crystal thin films have been investigated by a non-equilibrium molecular dynamics (NEMD) simulation method. The Stillinger-Weber potential model was employed to describe the interaction between atoms in the germanium single-crystal thin films. Taking structural characteristics and heat transfer mechanism of the germanium single-crystal thin films, a steady heat transfer model was framed. The results of calculations demonstrate that the in-plane thermal conductivities of germanium single-crystal thin films show an obvious size effect, which increases with increasing of thin film thickness and decreases with increasing of temperature. Comparing with the cross-plane thermal conductivity, the simulation results prove that the thermal conductivities of germanium single-crystal thin films have anisotropic characteristics.
15 Secondary Electron Emission Coefficient from Metal Deuteride Bombarded by Medium-Low-Energy Proton
Chen Jialin
,
Li Ming
,
Wang Shiyao
,
Shao Jianxiong
,
Tan Xiaohua
,
Jin Dazhi
,
Xiang Wei
,
Cui Ying
,
Chen Ximeng
2015, 44(3):660-664.
Abstract:
The secondary electron emission coefficient γ has been measured for ZrD1.74 and TiD1.70 material bombarded with proton of energies between 20 and 220 keV. It is found that in the energy range the coefficient is proportional to the electron stopping power for each sample when the beam density is 20 nA/cm2, except that the proportion factor Λ is about 50% lager than the Sternglass theory for the clean deuteride in this situation. Layer of impurity molecule adsorbed on the surface of the sample influences the coefficient γ. It is when the energy of incident proton is 100 keV and beam density is 7 μA/cm2 that the coefficient γ and the factor Λ fall steeply in the first 100 seconds when the beam bombarded sample and then become steady gradually, and eventually they are in good agreement with the Sternglass theory.
The secondary electron emission coefficient γ has been measured for ZrD1.74 and TiD1.70 material bombarded with proton of energies between 20 and 220 keV. It is found that in the energy range the coefficient is proportional to the electron stopping power for each sample when the beam density is 20 nA/cm2, except that the proportion factor Λ is about 50% lager than the Sternglass theory for the clean deuteride in this situation. Layer of impurity molecule adsorbed on the surface of the sample influences the coefficient γ. It is when the energy of incident proton is 100 keV and beam density is 7 μA/cm2 that the coefficient γ and the factor Λ fall steeply in the first 100 seconds when the beam bombarded sample and then become steady gradually, and eventually they are in good agreement with the Sternglass theory.
Zhao Hengzhang
,
Xi Zhengping
,
Guo Dizi
,
Zhao Bin
,
Yang Yingli
,
Mao Xiaonan
,
Sun Jun
,
Xiao Lin
2015, 44(3):671-675.
Abstract:
A rotary piercing technique is one of the effective methods to fabricate seamless tube of less-deformable alloy. The research on the technique using the rotary piercing method to produce Ti26 high-strength titanium tube was performed. The distribution of strain and parameters during rotary piercing was analyzed. Microstructure, properties and fracture surface of the tube were studied after annealing treatment in argon, induction and vacuum. The results show that the high-quality tube of β titanium alloy can be obtained by the rotary piercing technique, and the induction annealing technique is an efficient heat treatment for the tube.
A rotary piercing technique is one of the effective methods to fabricate seamless tube of less-deformable alloy. The research on the technique using the rotary piercing method to produce Ti26 high-strength titanium tube was performed. The distribution of strain and parameters during rotary piercing was analyzed. Microstructure, properties and fracture surface of the tube were studied after annealing treatment in argon, induction and vacuum. The results show that the high-quality tube of β titanium alloy can be obtained by the rotary piercing technique, and the induction annealing technique is an efficient heat treatment for the tube.
2015, 44(3):676-680.
Abstract:
Effects of high temperature thermomechanical treatment on microstructure and hardness of Ti-1300 alloy under isothermal deformation condition were investigated by means of optical microscope (OM), scanning electron microscopy (SEM), thermal simulation testing machine (Gleeble-3800) and Vickers hardness tester (IMVS-1000JMT2). The results show that high temperature thermomechanical treatment can markedly refine the microstructure and improve the mechanical property of Ti-1300 alloy. Microstructure observation of the hot rolled and hot compressed samples indicates that the tendency of the coarse and elongated grains recovering to equiaxed shape is more obvious, and the microstructure of Ti-1300 alloy after quenching plus aging and solution plus aging treatment is composed of a mixture of primary α phase (αp), secondary α phase (αs) and β phase. The αp phase is mainly distributed in the grain boundary, but the αs phase is mainly in the β matrix after aging treatment. The hardness of the alloy under quenching plus aging is increased due to the growth of αs phase and the remarkable refining of αp phase in width.
Effects of high temperature thermomechanical treatment on microstructure and hardness of Ti-1300 alloy under isothermal deformation condition were investigated by means of optical microscope (OM), scanning electron microscopy (SEM), thermal simulation testing machine (Gleeble-3800) and Vickers hardness tester (IMVS-1000JMT2). The results show that high temperature thermomechanical treatment can markedly refine the microstructure and improve the mechanical property of Ti-1300 alloy. Microstructure observation of the hot rolled and hot compressed samples indicates that the tendency of the coarse and elongated grains recovering to equiaxed shape is more obvious, and the microstructure of Ti-1300 alloy after quenching plus aging and solution plus aging treatment is composed of a mixture of primary α phase (αp), secondary α phase (αs) and β phase. The αp phase is mainly distributed in the grain boundary, but the αs phase is mainly in the β matrix after aging treatment. The hardness of the alloy under quenching plus aging is increased due to the growth of αs phase and the remarkable refining of αp phase in width.
2015, 44(3):688-691.
Abstract:
TiC/TiB2-FeNiCr composites enhanced by TiC particles and TiC-TiB2 multiphase particles were in-situ synthesized by thermite reaction. The microstructure and phase structure were investigated by electron probe microanalysis (EPMA), scanning electron microscopy (SEM), transmission electron microscope (TEM) and X-ray diffraction (XRD). The hardness and wear resistance were tested by the Vickers indentation method and friction-wear testers, respectively. Results show that the TiC/TiB2-FeNiCr composites are composed of TiC, TiC-TiB2 multiphase particles, Cr7C3, NiAl and α-FeNiCr. The Vickers hardness of composites is 13132.5 MPa. The composite mass wear loss is 4.2 mg after wearing for 1 h with 20 N force and that is nearly one third of the mass loss of 0.45C% steel.
TiC/TiB2-FeNiCr composites enhanced by TiC particles and TiC-TiB2 multiphase particles were in-situ synthesized by thermite reaction. The microstructure and phase structure were investigated by electron probe microanalysis (EPMA), scanning electron microscopy (SEM), transmission electron microscope (TEM) and X-ray diffraction (XRD). The hardness and wear resistance were tested by the Vickers indentation method and friction-wear testers, respectively. Results show that the TiC/TiB2-FeNiCr composites are composed of TiC, TiC-TiB2 multiphase particles, Cr7C3, NiAl and α-FeNiCr. The Vickers hardness of composites is 13132.5 MPa. The composite mass wear loss is 4.2 mg after wearing for 1 h with 20 N force and that is nearly one third of the mass loss of 0.45C% steel.
2015, 44(3):692-696.
Abstract:
Micro-arc oxidation coatings on biomedical titanium alloys were fabricated in an aqueous solution of Na2SiO3 at different impulse frequency. The morphology, phase composition, wear resistance and corrosion resistance of the MAO coating were studied by scanning electron microscope (SEM), X-ray diffractometry, CETR UMT Multi-Specimen Test System and IVIUM Electrochemical Workstation. The results show that the MAO coating has a large number of micropores and it is mainly composed of anatase and rutile TiO2. Within the experimental impulse frequency range, the porosity of the MAO coatings increases first, and then decreases with the frequency increasing; however, the average pore size decreases first, and then increases. The thickness of coatings decreases with the rising of frequency. When the frequency is kept at 700 Hz, the surface morphology is smooth and micropores of the MAO coating are distributed homogenously, the porosity reaches the maximum value 11.04%, and the average pore size reaches the minimum value 0.86 μm; meanwhile the best wear and corrosion resistance is obtained.
Micro-arc oxidation coatings on biomedical titanium alloys were fabricated in an aqueous solution of Na2SiO3 at different impulse frequency. The morphology, phase composition, wear resistance and corrosion resistance of the MAO coating were studied by scanning electron microscope (SEM), X-ray diffractometry, CETR UMT Multi-Specimen Test System and IVIUM Electrochemical Workstation. The results show that the MAO coating has a large number of micropores and it is mainly composed of anatase and rutile TiO2. Within the experimental impulse frequency range, the porosity of the MAO coatings increases first, and then decreases with the frequency increasing; however, the average pore size decreases first, and then increases. The thickness of coatings decreases with the rising of frequency. When the frequency is kept at 700 Hz, the surface morphology is smooth and micropores of the MAO coating are distributed homogenously, the porosity reaches the maximum value 11.04%, and the average pore size reaches the minimum value 0.86 μm; meanwhile the best wear and corrosion resistance is obtained.
2015, 44(3):703-707.
Abstract:
Highly ordered and size controllable ZnO nanorod arrays were prepared on Ti substrate through a hydrothermal method, and then the biocompatible PDLLA coating was self-assembled onto the surface of the prepared nanorod arrays via electrostatic adsorption process. SEM, MTT and LDH methods were used to characterize the morphology and biological activity of cells. The results show that cells on the ZnO nanorod arrays are round-like without spreading; while after the modification of PDLLA, there are the largest amount of cells on the modified nanorod arrays, the extracellular matrix become well-spread with many filopodia embedded into the gaps of the array structure, and the cell activity is significantly higher than that of ZnO nanorod arrays and titanium film. It is concluded that the PDLLA coating can improve the biocompatibility of the material to provide a suitable microenvironment for cell growth, and effectively promote the adhesion and proliferation of cells.
Highly ordered and size controllable ZnO nanorod arrays were prepared on Ti substrate through a hydrothermal method, and then the biocompatible PDLLA coating was self-assembled onto the surface of the prepared nanorod arrays via electrostatic adsorption process. SEM, MTT and LDH methods were used to characterize the morphology and biological activity of cells. The results show that cells on the ZnO nanorod arrays are round-like without spreading; while after the modification of PDLLA, there are the largest amount of cells on the modified nanorod arrays, the extracellular matrix become well-spread with many filopodia embedded into the gaps of the array structure, and the cell activity is significantly higher than that of ZnO nanorod arrays and titanium film. It is concluded that the PDLLA coating can improve the biocompatibility of the material to provide a suitable microenvironment for cell growth, and effectively promote the adhesion and proliferation of cells.
2015, 44(3):708-712.
Abstract:
Bonding between tungsten and 0Cr13Al steel using a Cu/90W-5Ni-5Co powder mixtures/Ni multi-interlayer, was carried out in vacuum for 60 min at 1120 oC with a pressure of 5 MPa. The microstructures, composition distribution and fracture characteristics of the joints were studied by SEM and EDS. Joint properties were tested by shear experiments and thermal shock test. The results show that the joints comprise of tungsten/Cu-Ni-Co/tungsten heavy alloy/Ni/steel. Among them, the tungsten heavy alloy sub-layer, which is composed of uniformly distributed tungsten phase and Ni-Co matrix, is formed by solid phase sintering of 90W-5Ni-5Co powder mixtures. Sound bonding between tungsten and tungsten heavy alloy sub-layer are realized based on the transient liquid phase bonding mechanism. The average shear strength of 286 MPa has been obtained, and all the joints fracture at bonding zone of tungsten heavy alloy sub-layer and Ni sub-layer during shear testing. The results of the thermal shock tests indicate that all joints could withstand 60 cycles from 700 oC to room temperature in water.
Bonding between tungsten and 0Cr13Al steel using a Cu/90W-5Ni-5Co powder mixtures/Ni multi-interlayer, was carried out in vacuum for 60 min at 1120 oC with a pressure of 5 MPa. The microstructures, composition distribution and fracture characteristics of the joints were studied by SEM and EDS. Joint properties were tested by shear experiments and thermal shock test. The results show that the joints comprise of tungsten/Cu-Ni-Co/tungsten heavy alloy/Ni/steel. Among them, the tungsten heavy alloy sub-layer, which is composed of uniformly distributed tungsten phase and Ni-Co matrix, is formed by solid phase sintering of 90W-5Ni-5Co powder mixtures. Sound bonding between tungsten and tungsten heavy alloy sub-layer are realized based on the transient liquid phase bonding mechanism. The average shear strength of 286 MPa has been obtained, and all the joints fracture at bonding zone of tungsten heavy alloy sub-layer and Ni sub-layer during shear testing. The results of the thermal shock tests indicate that all joints could withstand 60 cycles from 700 oC to room temperature in water.
2015, 44(3):723-726.
Abstract:
ZrB2 thin films are used as neutron burnable absorbers of nuclear reactor. In this paper, ZrB2 thin films were prepared on surfaces of Si(111) and UO2 fuel elements by magnetron sputtering. The microstructures of films were observed with scanning electron microscope (SEM). The phase constituents and compositions of ZrB2 films were analyzed by X-ray diffraction (XRD), X-ray energy dispersion spectroscope (EDS) and X-ray Photoelectron Spectroscopy (XPS). This paper has focused its efforts on the adherence quality through thermal shock and nano scratch tests. Results show that films with dense growth deposited on Si(111) and UO2 substrates are uniform and well adhered to the substrates. The films are consisted of pure ZrB2, and only Zr and B elements are detected. The critical load of films is about 455 mN.
ZrB2 thin films are used as neutron burnable absorbers of nuclear reactor. In this paper, ZrB2 thin films were prepared on surfaces of Si(111) and UO2 fuel elements by magnetron sputtering. The microstructures of films were observed with scanning electron microscope (SEM). The phase constituents and compositions of ZrB2 films were analyzed by X-ray diffraction (XRD), X-ray energy dispersion spectroscope (EDS) and X-ray Photoelectron Spectroscopy (XPS). This paper has focused its efforts on the adherence quality through thermal shock and nano scratch tests. Results show that films with dense growth deposited on Si(111) and UO2 substrates are uniform and well adhered to the substrates. The films are consisted of pure ZrB2, and only Zr and B elements are detected. The critical load of films is about 455 mN.
Pan Hucheng
,
Pan Fusheng
,
Zhang Lei
,
Peng Jian
,
Wu Lu
,
Lü Binjiang
,
Huang Meina
,
Zhao Chaoyong
2015, 44(3):727-732.
Abstract:
Mg-3Al-xSr (x=0.1~0.9 wt%) alloys were prepared by a traditional cast method. Microstructures, electrical conductivities and micro-hardness of the present alloys in as-cast and as-heat treated states were studied by means of optical microscope, SEM, XRD, electrical conductivity meter and micro-hardness measuring instruments. The results show that Al4Sr phase is formed with little addition of Sr (<0.1 wt%). With increasing content of Sr, the electrical conductivity of as-cast Mg-Al-Sr alloys increases, and Mg-Al-Sr ternary phase (τ phase) is formed. After high temperature heat treatment at 400 oC, τ phase would decompose to Al4Sr phase, and the corresponding electrical conductivity of Mg-Al-Sr alloys increases with the heating time increasing. Vickers hardness of the as-cast alloy decreases slightly with a small amount of Sr addition (<0.1 wt%). With the increasing content of Sr (>0.1 wt%), the hardness of the alloys increases first, reaching the peak hardness at 0.6 wt% Sr and then decreases. Moreover, the high temperature treatment would decrease the corresponding hardness for as-cast alloys.
Mg-3Al-xSr (x=0.1~0.9 wt%) alloys were prepared by a traditional cast method. Microstructures, electrical conductivities and micro-hardness of the present alloys in as-cast and as-heat treated states were studied by means of optical microscope, SEM, XRD, electrical conductivity meter and micro-hardness measuring instruments. The results show that Al4Sr phase is formed with little addition of Sr (<0.1 wt%). With increasing content of Sr, the electrical conductivity of as-cast Mg-Al-Sr alloys increases, and Mg-Al-Sr ternary phase (τ phase) is formed. After high temperature heat treatment at 400 oC, τ phase would decompose to Al4Sr phase, and the corresponding electrical conductivity of Mg-Al-Sr alloys increases with the heating time increasing. Vickers hardness of the as-cast alloy decreases slightly with a small amount of Sr addition (<0.1 wt%). With the increasing content of Sr (>0.1 wt%), the hardness of the alloys increases first, reaching the peak hardness at 0.6 wt% Sr and then decreases. Moreover, the high temperature treatment would decrease the corresponding hardness for as-cast alloys.
2015, 44(3):743-747.
Abstract:
LiNi1/3Co1/3-xMn1/3ZnxO2 (x=0, 1/24, 2/24 and 4/24) cathode material for lithium-ion battery was synthesized by a sol-gel method. The results of XRD and SEM show that Zn doping does not change the α-NaFeO2 layer structure of LiNi1/3Co1/3Mn1/3O2, and impurity phases occur when the doped amount reaches 4/24. Electrochemical studies indicate that when the doped Zn content is 2/24, the initial discharge capacity of LiNi1/3Co1/3Mn1/3O2 decreases from 169.2 mAh·g-1 of the undoped material to 160.1 mAh·g-1. The cycling performance, however, is significantly improved. Compared with undoped material, the capacity retention rate of the sample of LiNil/3Col/3-xMnl/3ZnxO2 with x=2/24 increases from 89.2% to 97% after 30 cycles. The same sample was charged and discharged again at 20 mA·g?1 and the corresponding discharge specific capacity was restored to 150.3 mAh·g?1 after 20 cycles in different current densities of 20, 40, 60 and 80 mA·g-1.
LiNi1/3Co1/3-xMn1/3ZnxO2 (x=0, 1/24, 2/24 and 4/24) cathode material for lithium-ion battery was synthesized by a sol-gel method. The results of XRD and SEM show that Zn doping does not change the α-NaFeO2 layer structure of LiNi1/3Co1/3Mn1/3O2, and impurity phases occur when the doped amount reaches 4/24. Electrochemical studies indicate that when the doped Zn content is 2/24, the initial discharge capacity of LiNi1/3Co1/3Mn1/3O2 decreases from 169.2 mAh·g-1 of the undoped material to 160.1 mAh·g-1. The cycling performance, however, is significantly improved. Compared with undoped material, the capacity retention rate of the sample of LiNil/3Col/3-xMnl/3ZnxO2 with x=2/24 increases from 89.2% to 97% after 30 cycles. The same sample was charged and discharged again at 20 mA·g?1 and the corresponding discharge specific capacity was restored to 150.3 mAh·g?1 after 20 cycles in different current densities of 20, 40, 60 and 80 mA·g-1.
Zhang Xuefeng
,
Shi Yao
,
Ma Qiang
,
Liu Yanli
,
Shi Mengfei
,
Li Yongfeng
,
Wang Gaofeng
,
Zhao Zengru
2015, 44(3):748-752.
Abstract:
(PrNd)14-xMMxFe80.4B5.6 permanent magnet materials were prepared from mixed rare earth (MM) of Bayan obo. 30% of PrNd alloy was replaced by MM. The material exhibits a remanence of 1.18 T, a maximum energy product 238.08 kJ/m3, and an intrinsic coercivity of remanence 726.75 kA/m. Oxide of La and Ce exists in rich rare earth phase and there are (NdCe)2Fe14B and (NdLa)2Fe14B in main phase. Compared with others magnets, La content in (PrNd)14-xMMxFe80.4B5.6 magnet is higher when getting the similar magnetic performance. La, Ce, Pr and Nd in the mixed rare earth magnet act together, so MM is used efficiently. Domain structure change was observed by high field Kerr microscopy. The domain wall could be through the grain boundary, and the magnetic domain is easy to spread under magnetic field.
(PrNd)14-xMMxFe80.4B5.6 permanent magnet materials were prepared from mixed rare earth (MM) of Bayan obo. 30% of PrNd alloy was replaced by MM. The material exhibits a remanence of 1.18 T, a maximum energy product 238.08 kJ/m3, and an intrinsic coercivity of remanence 726.75 kA/m. Oxide of La and Ce exists in rich rare earth phase and there are (NdCe)2Fe14B and (NdLa)2Fe14B in main phase. Compared with others magnets, La content in (PrNd)14-xMMxFe80.4B5.6 magnet is higher when getting the similar magnetic performance. La, Ce, Pr and Nd in the mixed rare earth magnet act together, so MM is used efficiently. Domain structure change was observed by high field Kerr microscopy. The domain wall could be through the grain boundary, and the magnetic domain is easy to spread under magnetic field.
2015, 44(3):753-758.
Abstract:
Poly(N-vinyl-2-pyrrolidone) (PVP)-protected Au/Ni bimetallic nanoparticles (BNPs) were prepared using a chemical reduction method. The obtained BNPs were characterized by Ultraviolet-visible spectrophotometry (UV-Vis) and transmission electron microscopy (TEM). The effects of metal compositions on the hydrolysis reaction of the alkaline NaBH4 solution were studied. The results indicate that the prepared Au/Ni BNPs have an average size of 2.9~4.2 nm. The activities of BNPs are much higher than that of Au and Ni monometallic nanoparticles (MNPs). Among all the MNPs and BNPs, Au/Ni BNPs with atomic ratio of 50/50 display the highest catalytic activity, showing a high hydrogen release rate of 550 mol-H2·h-1·mol-M-1 at 30 oC. The catalytic activity of the Au/Ni BNPs higher than that of corresponding MNPs can be ascribed to electronic charge transfer effects. X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) show that Au atoms are indeed negatively charged, while the Ni atoms have positive charges due to the electron donation from the Ni atoms to Au atoms. The positively charged Ni atoms and negatively charged Au atoms act as catalytic active sites for the hydrolysis reaction of the alkaline NaBH4 solution. Au50Ni50 BNPs display a low apparent activation energy of 61.9 kJ/mol.
Poly(N-vinyl-2-pyrrolidone) (PVP)-protected Au/Ni bimetallic nanoparticles (BNPs) were prepared using a chemical reduction method. The obtained BNPs were characterized by Ultraviolet-visible spectrophotometry (UV-Vis) and transmission electron microscopy (TEM). The effects of metal compositions on the hydrolysis reaction of the alkaline NaBH4 solution were studied. The results indicate that the prepared Au/Ni BNPs have an average size of 2.9~4.2 nm. The activities of BNPs are much higher than that of Au and Ni monometallic nanoparticles (MNPs). Among all the MNPs and BNPs, Au/Ni BNPs with atomic ratio of 50/50 display the highest catalytic activity, showing a high hydrogen release rate of 550 mol-H2·h-1·mol-M-1 at 30 oC. The catalytic activity of the Au/Ni BNPs higher than that of corresponding MNPs can be ascribed to electronic charge transfer effects. X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) show that Au atoms are indeed negatively charged, while the Ni atoms have positive charges due to the electron donation from the Ni atoms to Au atoms. The positively charged Ni atoms and negatively charged Au atoms act as catalytic active sites for the hydrolysis reaction of the alkaline NaBH4 solution. Au50Ni50 BNPs display a low apparent activation energy of 61.9 kJ/mol.
2015, 44(3):759-762.
Abstract:
Ga and K dual doped Bi0.5Sb1.5Te3 thermoelectric materials were prepared by vacuum melting and hot pressing. XRD results indicate that all the characteristic peaks of the bulk Ga0.02Bi0.5Sb1.48-xKxTe3 can be indexed into Bi0.5Sb1.5Te3, but the diffraction peaks of the dual doped samples slightly lean to the left. Hot-pressed bulk materials exhibit the (00l) preferred orientation. SEM morphology shows that microstructure is dense and layered structure. The Seebeck coefficient of Bi0.5Sb1.5Te3 near the room temperature can be improved to some extent by Ga and K dual doping. The electrical conductivity of dual doped samples can be improved in different degrees, and electrical conductivity of Ga0.02Bi0.5Sb1.42K0.06Te3 samples is improved obviously. In the whole measured temperature range of 300~500 K, the thermal conductivity of the dual doped samples is higher than that of Bi0.5Sb1.5Te3. ZT values of the dual doped samples are improved at near 300 K, and the ZT value of Ga0.02Bi0.5Sb1.42K0.06Te3 sample reaches 1.5 at 300 K.
Ga and K dual doped Bi0.5Sb1.5Te3 thermoelectric materials were prepared by vacuum melting and hot pressing. XRD results indicate that all the characteristic peaks of the bulk Ga0.02Bi0.5Sb1.48-xKxTe3 can be indexed into Bi0.5Sb1.5Te3, but the diffraction peaks of the dual doped samples slightly lean to the left. Hot-pressed bulk materials exhibit the (00l) preferred orientation. SEM morphology shows that microstructure is dense and layered structure. The Seebeck coefficient of Bi0.5Sb1.5Te3 near the room temperature can be improved to some extent by Ga and K dual doping. The electrical conductivity of dual doped samples can be improved in different degrees, and electrical conductivity of Ga0.02Bi0.5Sb1.42K0.06Te3 samples is improved obviously. In the whole measured temperature range of 300~500 K, the thermal conductivity of the dual doped samples is higher than that of Bi0.5Sb1.5Te3. ZT values of the dual doped samples are improved at near 300 K, and the ZT value of Ga0.02Bi0.5Sb1.42K0.06Te3 sample reaches 1.5 at 300 K.
2015, 44(3):763-767.
Abstract:
This work applied lanthanide ions to simulate the actinides in order to use the room temperature ionic liquids as the electrolytes as a substitute for chloride high temperature molten salt to attain the goal of reducing the actinide such as uranium or plutonium?in the nonaqueous reprocessing applications of spent nuclear fuel. The electrochemical behavior of La(III) in the ionic liquid, N-methyl-N-propylpiperidinium bis(trifluoromethylsulfonyl)imide (MPPiNTf2), has been investigated by cyclic voltammetry. The results indicate that the reduction of La(III) is irreversible. The diffusion coefficient and the energy of activation of La(III) in ionic liquid MPPiNTf2 are 2.79×10-7 cm2/s at 323 K and 99.4 kJ/mol, respectively. Controlled potential electrolysis of a solution of La(Ⅲ) in MPPiNTf2 at –2.9 V (vs.Pd) results in the deposition of metallic lanthanum.
This work applied lanthanide ions to simulate the actinides in order to use the room temperature ionic liquids as the electrolytes as a substitute for chloride high temperature molten salt to attain the goal of reducing the actinide such as uranium or plutonium?in the nonaqueous reprocessing applications of spent nuclear fuel. The electrochemical behavior of La(III) in the ionic liquid, N-methyl-N-propylpiperidinium bis(trifluoromethylsulfonyl)imide (MPPiNTf2), has been investigated by cyclic voltammetry. The results indicate that the reduction of La(III) is irreversible. The diffusion coefficient and the energy of activation of La(III) in ionic liquid MPPiNTf2 are 2.79×10-7 cm2/s at 323 K and 99.4 kJ/mol, respectively. Controlled potential electrolysis of a solution of La(Ⅲ) in MPPiNTf2 at –2.9 V (vs.Pd) results in the deposition of metallic lanthanum.
2015, 44(3):768-774.
Abstract:
Precipitation strengthening Ni-Fe based superalloy GH4169 has been widely used in aircraft engine, petroleum, nuclear industrial etc. Previous papers indicated that the phase transition from γ" to δ was performed when the temperature exceeded 650 oC. The reduction of strengthening phase amount degraded the mechanical properties and the application range. This paper summarized the characteristics of composition, microstructure and precipitated phases of GH4169 alloy. The influences of heat treatment and heat deformation process on the stability of microstructure and mechanical properties were reviewed, and the mechanical properties were affected by the morphologies and distribution of δ phase. The composition features of the modified alloy were concluded. In addition, the future trends and the possibility of GH4169 alloy to satisfy the use requirement for the 700 oC advanced ultra-supercritical power plants were proposed.
Precipitation strengthening Ni-Fe based superalloy GH4169 has been widely used in aircraft engine, petroleum, nuclear industrial etc. Previous papers indicated that the phase transition from γ" to δ was performed when the temperature exceeded 650 oC. The reduction of strengthening phase amount degraded the mechanical properties and the application range. This paper summarized the characteristics of composition, microstructure and precipitated phases of GH4169 alloy. The influences of heat treatment and heat deformation process on the stability of microstructure and mechanical properties were reviewed, and the mechanical properties were affected by the morphologies and distribution of δ phase. The composition features of the modified alloy were concluded. In addition, the future trends and the possibility of GH4169 alloy to satisfy the use requirement for the 700 oC advanced ultra-supercritical power plants were proposed.
2015, 44(3):775-780.
Abstract:
The refining effect of hydrogen plasma arc melting (HPAM) on refractory metals has been summarized. The structure and principle of a plasma arc melting furnace were introduced and the advantages of HPAM on refining of refractory metals were also discussed. At last H2 involved in the plasma arc melting are considered to play an important role in the melting process.
The refining effect of hydrogen plasma arc melting (HPAM) on refractory metals has been summarized. The structure and principle of a plasma arc melting furnace were introduced and the advantages of HPAM on refining of refractory metals were also discussed. At last H2 involved in the plasma arc melting are considered to play an important role in the melting process.
