Volume 36,Issue 5,2007 Table of Contents
2007, 36(5):753-758.
Abstract:
Ti-based bulk metallic glasses (BMGs) developed in the past decade have been reviewed in terms of their compositions, glass-forming abilities and mechanical properties. The cast defects in the BMG samples, which significantly deteriorate the mechanical properties, are discussed and summarized based on the experimental results in the literature. Some results on the cast nanostructured Ti alloys with dendritic ductile beta phase are also reviewed. A special composite microstructure, dendritic beta-Ti(M) (in micrometer size) + rod-like eutectic beta-Ti/gamma-TiCu (in nanometer size), has been obtained in the as-cast cylinders smaller than 5 mm in diameter in the Ti-Cu-Ni-Sn-Ta(Nb) systems. The Ti alloys with such composite microstructure exhibit very high strength and remarkable plasticity.
Ti-based bulk metallic glasses (BMGs) developed in the past decade have been reviewed in terms of their compositions, glass-forming abilities and mechanical properties. The cast defects in the BMG samples, which significantly deteriorate the mechanical properties, are discussed and summarized based on the experimental results in the literature. Some results on the cast nanostructured Ti alloys with dendritic ductile beta phase are also reviewed. A special composite microstructure, dendritic beta-Ti(M) (in micrometer size) + rod-like eutectic beta-Ti/gamma-TiCu (in nanometer size), has been obtained in the as-cast cylinders smaller than 5 mm in diameter in the Ti-Cu-Ni-Sn-Ta(Nb) systems. The Ti alloys with such composite microstructure exhibit very high strength and remarkable plasticity.
2007, 36(5):759-763.
Abstract:
Sr2CeO4 is not only a novel blue-emitting phosphor holding important application potential, but also a good host lattice for trivalent rare-earth activators. In recent years, more attentions were paid to the photoluminescence performance of the Sr2CeO4 doped with rare-earth. The crystal structure and spectral properties are analyzed for these phosphors. The luminescent performance of Sr2CeO4 phosphors doped with Eu3+, Sm3+, Dy3+ with tunable emission colors is reviewed. Some suggestions are proposed for the further research.
Sr2CeO4 is not only a novel blue-emitting phosphor holding important application potential, but also a good host lattice for trivalent rare-earth activators. In recent years, more attentions were paid to the photoluminescence performance of the Sr2CeO4 doped with rare-earth. The crystal structure and spectral properties are analyzed for these phosphors. The luminescent performance of Sr2CeO4 phosphors doped with Eu3+, Sm3+, Dy3+ with tunable emission colors is reviewed. Some suggestions are proposed for the further research.
2007, 36(5):764-768.
Abstract:
The in-situ TiC particles reinforced Ti-matrix composites were fabricated by melting-casting. The mechanisms of crack forming and propagation were investigated during dynamic tension under static load by SEM. The results showed that microcracks easily appeared on the surface of TiC particles with stress concentration. The microcracks in advantageous orientation propagated continuously mainly by self-propagation and combination with ambient cracks among the micocracks in different position, forming the dominant crack by connection with surrounding cracks. When the crack propagation was baffled, new cracks formed on the front TiC particle in front of cracks or plastic pits formed in the matrix, and the cracks were connected with each other by propagating, so that the samples losed the stability and fractured rapidly after the cracks propagated to some extent. A model of crack forming and propagation was established according to the results.
The in-situ TiC particles reinforced Ti-matrix composites were fabricated by melting-casting. The mechanisms of crack forming and propagation were investigated during dynamic tension under static load by SEM. The results showed that microcracks easily appeared on the surface of TiC particles with stress concentration. The microcracks in advantageous orientation propagated continuously mainly by self-propagation and combination with ambient cracks among the micocracks in different position, forming the dominant crack by connection with surrounding cracks. When the crack propagation was baffled, new cracks formed on the front TiC particle in front of cracks or plastic pits formed in the matrix, and the cracks were connected with each other by propagating, so that the samples losed the stability and fractured rapidly after the cracks propagated to some extent. A model of crack forming and propagation was established according to the results.
2007, 36(5):769-773.
Abstract:
Magnesium matrix composite reinforced by titanium alloy (Ti-6Al-4V) particulate was fabricated by powder metallurgy route. The samples of composite were hot-extruded with an ultra-deformation ratio of 225:1. The microstructures of extruded samples were investigated using optical microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results showed that the Ti-6Al-4V particulates were apparently elongated along the extrusion direction, thus increased its reinforcing effect on the matrix. The ultra-deformation could markedly decrease the grain sizes of the composite matrix, and greatly improve the homogeneity of microstructures when compared with a lower ratio of extrusion deformation; in addition, the oxide layers on the surface of original Mg particles were effectively broken and dispersed randomly in the vicinity of Mg-Mg interfaces. It produced an oxidedispersion-strengthening (ODS) effect, further reinforced the matrix as a kind of secondary reinforcement.
Magnesium matrix composite reinforced by titanium alloy (Ti-6Al-4V) particulate was fabricated by powder metallurgy route. The samples of composite were hot-extruded with an ultra-deformation ratio of 225:1. The microstructures of extruded samples were investigated using optical microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results showed that the Ti-6Al-4V particulates were apparently elongated along the extrusion direction, thus increased its reinforcing effect on the matrix. The ultra-deformation could markedly decrease the grain sizes of the composite matrix, and greatly improve the homogeneity of microstructures when compared with a lower ratio of extrusion deformation; in addition, the oxide layers on the surface of original Mg particles were effectively broken and dispersed randomly in the vicinity of Mg-Mg interfaces. It produced an oxidedispersion-strengthening (ODS) effect, further reinforced the matrix as a kind of secondary reinforcement.
2007, 36(5):774-777.
Abstract:
The effects of heat input on the laser beam welding residual stress and distortion of TC4 titanium alloy were investigated by finite element analysis and experimental tests. The internal relationships of residual stress, deformation and heat input were further investigated by the metallographic section of weld. The results showed that the tensile stresses produced in the longitudinal direction of welded joints were about 700 MPa-850 MPa, but only 50 MPa-80 MPa for the transverse tensile stresses. The tensile region of longitudinal residual stress was widened and the stress peak was decreased, but the magnitude of transverse tensile stress was increased when the heat input increasing. At the same time, the angular distortion was decreased and the transverse shrinkage deformation was increased when welding at above a critical specification. As the welding specimens were fully penetrated, the effects of heat input on the angular distortion were decreased.
The effects of heat input on the laser beam welding residual stress and distortion of TC4 titanium alloy were investigated by finite element analysis and experimental tests. The internal relationships of residual stress, deformation and heat input were further investigated by the metallographic section of weld. The results showed that the tensile stresses produced in the longitudinal direction of welded joints were about 700 MPa-850 MPa, but only 50 MPa-80 MPa for the transverse tensile stresses. The tensile region of longitudinal residual stress was widened and the stress peak was decreased, but the magnitude of transverse tensile stress was increased when the heat input increasing. At the same time, the angular distortion was decreased and the transverse shrinkage deformation was increased when welding at above a critical specification. As the welding specimens were fully penetrated, the effects of heat input on the angular distortion were decreased.
2007, 36(5):778-781.
Abstract:
The fretting wear characteristics of Titanium alloy TC11 in seawater are studied by a SRV wear machine. The effects and the lubrication media on the friction coefficient and the wear resistance are investigated. Results show that the friction coefficients turn stable with the increase of amplitude, and the volume-losses increase with the increase of the amount and amplitude of load. The wear mechanism is fatigue and peeling with grain abrasion for small amplitudes, and only grain abrasion for big amplitudes. Compared with in pure water, the friction coefficient decreases greatly even to 50% in seawater with a smaller volume-loss, exhibiting a negative interaction between corrosion and wear.
The fretting wear characteristics of Titanium alloy TC11 in seawater are studied by a SRV wear machine. The effects and the lubrication media on the friction coefficient and the wear resistance are investigated. Results show that the friction coefficients turn stable with the increase of amplitude, and the volume-losses increase with the increase of the amount and amplitude of load. The wear mechanism is fatigue and peeling with grain abrasion for small amplitudes, and only grain abrasion for big amplitudes. Compared with in pure water, the friction coefficient decreases greatly even to 50% in seawater with a smaller volume-loss, exhibiting a negative interaction between corrosion and wear.
2007, 36(5):782-785.
Abstract:
通过不同的热处理制度控制TMZF合金中的相组成和含量，利用XRD分析确定各种相结构。利用纳米压入测量仪测试了不同组织结构下的硬度和弹性模量。结果表明，当合金中存在ω相时，合金的的硬度和弹性模量最高，随着热处理温度的提高，合金中的ω相消失，代之而来的是α相，而且越接近β转变温度，α相含量越少，对应的弹性模量和硬度越来越低。对于Ti—Mo—Zr-Fe合金来说压入性能（硬度、弹性模量）与相成分之间存在着良好的匹配关系。
通过不同的热处理制度控制TMZF合金中的相组成和含量，利用XRD分析确定各种相结构。利用纳米压入测量仪测试了不同组织结构下的硬度和弹性模量。结果表明，当合金中存在ω相时，合金的的硬度和弹性模量最高，随着热处理温度的提高，合金中的ω相消失，代之而来的是α相，而且越接近β转变温度，α相含量越少，对应的弹性模量和硬度越来越低。对于Ti—Mo—Zr-Fe合金来说压入性能（硬度、弹性模量）与相成分之间存在着良好的匹配关系。
2007, 36(5):786-789.
Abstract:
研究了不同冷却方式（水冷，空冷和炉冷）对Ti-6Al—2Zr-2V-1Mo（质量分数，下同）ELI（TA15 ELI）合金43mm厚板双态组织中次生α片厚度，以及对该合金双态组织和等轴组织损伤容限性能的影响。结果表明：水冷时α片厚约1μm，空冷时α片厚为2μm～4μm，炉冷时α片过于增厚，几乎完全溶于等轴α相内，形成完全等轴组织。次生α相的变化对该合金的屈服强度和断裂韧性产生很大影响，但对疲劳裂纹扩展速率影响不大，疲劳裂纹主要以切过或沿等轴α相界面扩展。采用Paris（dα／dN=c（△Kn）^n公式对3种合金组织疲劳裂纹扩展数据进行拟合，其结果为：c=1-8×10^-8，n=3.12-3.28。
研究了不同冷却方式（水冷，空冷和炉冷）对Ti-6Al—2Zr-2V-1Mo（质量分数，下同）ELI（TA15 ELI）合金43mm厚板双态组织中次生α片厚度，以及对该合金双态组织和等轴组织损伤容限性能的影响。结果表明：水冷时α片厚约1μm，空冷时α片厚为2μm～4μm，炉冷时α片过于增厚，几乎完全溶于等轴α相内，形成完全等轴组织。次生α相的变化对该合金的屈服强度和断裂韧性产生很大影响，但对疲劳裂纹扩展速率影响不大，疲劳裂纹主要以切过或沿等轴α相界面扩展。采用Paris（dα／dN=c（△Kn）^n公式对3种合金组织疲劳裂纹扩展数据进行拟合，其结果为：c=1-8×10^-8，n=3.12-3.28。
2007, 36(5):790-793.
Abstract:
The hydrogen storage properties of La1.8Ca0.2Mg14Ni3 were modified by mechanical ball-milling with addition of x wt%Ti (x=0,5,10). X-ray diffraction (XRD), scanning electron microscopy (SEM) and hydrogen absorption/desorption tests were carried out to study the effect of Ti. The results show that the hydrogen storage properties of La1.8Ca0.2Mg14Ni3 are remarkably improved after ball-milling with addition of small amount of Ti. For the as-cast alloy, 6 cycles of hydriding/dehydriding are needed to activate it at 613 K, and the maximum hydrogen storage capacity is around 4.12 %. After modification by ball-milling with addition of Ti, the activation behavior and the hydrogen storage capacity and the absorption/desorption kinetics are all improved. The effective desorption capacities of the alloys with x=0, 5 and 10 at 613 K are 4.69 %,4.80% and 4.83%, respectively. As x=10, the alloys can absorb more than 3% hydrogen at 373 K, and 4.81 % hydrogen (97% of the maximum hydrogen storage capacity) at 600 K within 2 min. The microstructure analysis indicated that the titanium powder on the alloy surface played the role of surface-catalysis, accelerated the hydrogen decomposition and formation, and provided more channels for hydrogen diffusion from surface, were partly transformed into amorphous structure. As a result, the hydrogen storage properties of La1.8Ca0.2Mg14Ni3 were improved
The hydrogen storage properties of La1.8Ca0.2Mg14Ni3 were modified by mechanical ball-milling with addition of x wt%Ti (x=0,5,10). X-ray diffraction (XRD), scanning electron microscopy (SEM) and hydrogen absorption/desorption tests were carried out to study the effect of Ti. The results show that the hydrogen storage properties of La1.8Ca0.2Mg14Ni3 are remarkably improved after ball-milling with addition of small amount of Ti. For the as-cast alloy, 6 cycles of hydriding/dehydriding are needed to activate it at 613 K, and the maximum hydrogen storage capacity is around 4.12 %. After modification by ball-milling with addition of Ti, the activation behavior and the hydrogen storage capacity and the absorption/desorption kinetics are all improved. The effective desorption capacities of the alloys with x=0, 5 and 10 at 613 K are 4.69 %,4.80% and 4.83%, respectively. As x=10, the alloys can absorb more than 3% hydrogen at 373 K, and 4.81 % hydrogen (97% of the maximum hydrogen storage capacity) at 600 K within 2 min. The microstructure analysis indicated that the titanium powder on the alloy surface played the role of surface-catalysis, accelerated the hydrogen decomposition and formation, and provided more channels for hydrogen diffusion from surface, were partly transformed into amorphous structure. As a result, the hydrogen storage properties of La1.8Ca0.2Mg14Ni3 were improved
2007, 36(5):799-802.
Abstract:
The microstructure and hydrogen absorption and desorption properties of (V30Ti35Cr25Fe10)97.5Si2.5 alloy consisting of 75% BCC phase and 25% C14 Laves phase were investigated by X-ray, SEM and PCT measurement in this paper. The lattice parameters of BCC phase and Laves phase are 0.3021 nm (a), as well as 0.4920 nm (a) and 0.7996 nm (c), respectively. The alloy shows a good activation performance with a saturated hydrogen absorption amount up to 2.98 wt% within 5 min, and reacts with hydrogen immediately at room temperature duo to the large amount of Laves phase. The capacity of (V30Ti35Cr25Fe10)97.5Si2.5 at a given pressure agrees with the one calculated by the linear combination of its constituent phase.
The microstructure and hydrogen absorption and desorption properties of (V30Ti35Cr25Fe10)97.5Si2.5 alloy consisting of 75% BCC phase and 25% C14 Laves phase were investigated by X-ray, SEM and PCT measurement in this paper. The lattice parameters of BCC phase and Laves phase are 0.3021 nm (a), as well as 0.4920 nm (a) and 0.7996 nm (c), respectively. The alloy shows a good activation performance with a saturated hydrogen absorption amount up to 2.98 wt% within 5 min, and reacts with hydrogen immediately at room temperature duo to the large amount of Laves phase. The capacity of (V30Ti35Cr25Fe10)97.5Si2.5 at a given pressure agrees with the one calculated by the linear combination of its constituent phase.
2007, 36(5):803-807.
Abstract:
Texture was examed using XRD and low cycle fatigue property was analyzed using fatigue tester(25 kN) of MTS809A/T-type for Zr-4 alloy plate at room temperature in rolling direction and transverse direction, respectively, in this paper. Results show that the Zr-4 alloy plate has the obvious texture, and the low cycle fatigue property is better in rolling direction than in transverse direction. During the cycle deformation, only partial grains exhibited plastic deformation, where many dislocations and slip lines existed. The dislocations and slip lines in the deformed gains are denser in transverse direction than that in the rolling direction. The difference of low cycle fatigue lifes for the two samples is due to the texture in the Zr-4 alloy plate.
Texture was examed using XRD and low cycle fatigue property was analyzed using fatigue tester(25 kN) of MTS809A/T-type for Zr-4 alloy plate at room temperature in rolling direction and transverse direction, respectively, in this paper. Results show that the Zr-4 alloy plate has the obvious texture, and the low cycle fatigue property is better in rolling direction than in transverse direction. During the cycle deformation, only partial grains exhibited plastic deformation, where many dislocations and slip lines existed. The dislocations and slip lines in the deformed gains are denser in transverse direction than that in the rolling direction. The difference of low cycle fatigue lifes for the two samples is due to the texture in the Zr-4 alloy plate.
2007, 36(5):808-812.
Abstract:
在Gleeble-1500热／力模拟机上对Zr-4合金进行了热压缩试验，研究了其在温度750℃-950℃和应变速率0．005s^-1～50s^-1条件下的热变形行为。结果表明：热变形过程的流变应力可用双曲正弦本构关系来描述，平均激活能为377．79kJ／mol。根据材料动态模型，计算并分析了Zr-4合金的加工图。利用加工图确定了热变形的流变失稳区，并且获得了试验参数范围内的热变形过程的最佳工艺参数，其热加工温度930℃～950℃，应变速率为0．05s^-1～0．8s^-1和10s^-1-30s^-1的2个区域。
在Gleeble-1500热／力模拟机上对Zr-4合金进行了热压缩试验，研究了其在温度750℃-950℃和应变速率0．005s^-1～50s^-1条件下的热变形行为。结果表明：热变形过程的流变应力可用双曲正弦本构关系来描述，平均激活能为377．79kJ／mol。根据材料动态模型，计算并分析了Zr-4合金的加工图。利用加工图确定了热变形的流变失稳区，并且获得了试验参数范围内的热变形过程的最佳工艺参数，其热加工温度930℃～950℃，应变速率为0．05s^-1～0．8s^-1和10s^-1-30s^-1的2个区域。
2007, 36(5):813-816.
Abstract:
The wetting behavior and interracial interaction of Zr41 25Ti13.75Ni10Cu12. 5Be22. 5 molten on W were studied by the sessile drop method in high vacuum. Tungsten fiber reinforced Zr41.25Ti13.75Ni10Cu12.5Be22.5 bulk metallic glass matrix composite was fabricated by infiltration process. The results show that there is a good wettability in Zr41.25Ti13 .75Ni10Cu12.5Be22. 5 molten/W wetting system between 1053 K and 1173 K. Increase of wetting temperature resulted in the decrease of equilibrium contact angle and the increase of spreading rate and solution of W. It had little effects on the equilibrium contact angle and the equilibrium wetting time when increasing above 1173 K. Good wettability and rapid spread rate provided a wide operating space for fabricating tungsten fiber reinforced Zr41.25Ti13 75Ni10Cu12.5Be22. 5 bulk metallic glass matrix composite.
The wetting behavior and interracial interaction of Zr41 25Ti13.75Ni10Cu12. 5Be22. 5 molten on W were studied by the sessile drop method in high vacuum. Tungsten fiber reinforced Zr41.25Ti13.75Ni10Cu12.5Be22.5 bulk metallic glass matrix composite was fabricated by infiltration process. The results show that there is a good wettability in Zr41.25Ti13 .75Ni10Cu12.5Be22. 5 molten/W wetting system between 1053 K and 1173 K. Increase of wetting temperature resulted in the decrease of equilibrium contact angle and the increase of spreading rate and solution of W. It had little effects on the equilibrium contact angle and the equilibrium wetting time when increasing above 1173 K. Good wettability and rapid spread rate provided a wide operating space for fabricating tungsten fiber reinforced Zr41.25Ti13 75Ni10Cu12.5Be22. 5 bulk metallic glass matrix composite.
2007, 36(5):817-821.
Abstract:
A series of Cu-W alloys added with TiC particles were prepared by means of powder metallurgy-infiltration process. The effects of TiC addition on the microstructure and properties were investigated for the Cu-W alloys, respectively, including the static property and the vacuum breakdown property. The results showed that the hardness of W-Cu alloys increased with increasing percentage of TiC, while the electric conductivity changed slightly for TiC addition in the range of 0wt %-1.2wt%, but dramatical decreases were observed for TiC addition from 1.2wt% to 2wt%. The dielectric strength was improved and the chopping current of was decreased by TiC phase addition. The metallographic analysis of Cu-W alloys after vacuum breakdown showed that the splash of liquid copper was decreased because the TiC phase nailed on the skeletons of tungsten. The vacuum breakdown took place in interphase boundaries of copper and TiC with smaller cathode craters.
A series of Cu-W alloys added with TiC particles were prepared by means of powder metallurgy-infiltration process. The effects of TiC addition on the microstructure and properties were investigated for the Cu-W alloys, respectively, including the static property and the vacuum breakdown property. The results showed that the hardness of W-Cu alloys increased with increasing percentage of TiC, while the electric conductivity changed slightly for TiC addition in the range of 0wt %-1.2wt%, but dramatical decreases were observed for TiC addition from 1.2wt% to 2wt%. The dielectric strength was improved and the chopping current of was decreased by TiC phase addition. The metallographic analysis of Cu-W alloys after vacuum breakdown showed that the splash of liquid copper was decreased because the TiC phase nailed on the skeletons of tungsten. The vacuum breakdown took place in interphase boundaries of copper and TiC with smaller cathode craters.
2007, 36(5):822-824.
Abstract:
采用机械球磨的方法制备W-1％La2O3（质量分数，下同）复合粉体，将粉体在1823K烧结1h制备出La2O3增强钨合金。对材料的显微组织结构和力学性能进行分析，结果表明：显微组织均匀，氧化镧主要以微小的颗粒分布在钨-钨界面上，钨晶粒尺寸约为10μm～15μm：La2O3增强钨合金的抗弯强度值475MPa，在相同密度条件下，相对纯钨烧结体提高了35％。抗弯断口形貌表明，加入氧化镧颗粒后，钨合金的断裂方式发生了变化，由钨晶粒断裂为主转变为穿晶断裂和沿晶断裂的混合，同时分析讨论了氧化镧颗粒对合金组织性能的影响。
采用机械球磨的方法制备W-1％La2O3（质量分数，下同）复合粉体，将粉体在1823K烧结1h制备出La2O3增强钨合金。对材料的显微组织结构和力学性能进行分析，结果表明：显微组织均匀，氧化镧主要以微小的颗粒分布在钨-钨界面上，钨晶粒尺寸约为10μm～15μm：La2O3增强钨合金的抗弯强度值475MPa，在相同密度条件下，相对纯钨烧结体提高了35％。抗弯断口形貌表明，加入氧化镧颗粒后，钨合金的断裂方式发生了变化，由钨晶粒断裂为主转变为穿晶断裂和沿晶断裂的混合，同时分析讨论了氧化镧颗粒对合金组织性能的影响。
2007, 36(5):825-829.
Abstract:
The Mo-Al2O3 cermet granula films were deposited on stainless steel substrates by magnetron sputtering. The Maxwell-Garnett equivalent medium theory was used to analysis the optical constants of Mo-Al2O3 granular films. The optical constants, such as n and k, and their variations with wavelengths of from 300 nm to 800 nm were studied for the Mo-Al2O3 granular films based on the optical constants of bulk material and thin films of Mo and Al2O3. The possible reasons for the disagreement between theory and experiment were explained at the same time.
The Mo-Al2O3 cermet granula films were deposited on stainless steel substrates by magnetron sputtering. The Maxwell-Garnett equivalent medium theory was used to analysis the optical constants of Mo-Al2O3 granular films. The optical constants, such as n and k, and their variations with wavelengths of from 300 nm to 800 nm were studied for the Mo-Al2O3 granular films based on the optical constants of bulk material and thin films of Mo and Al2O3. The possible reasons for the disagreement between theory and experiment were explained at the same time.
2007, 36(5):830-834.
Abstract:
添加Nb可提高（Nd0.9Dy0.1）9.5Fe79Co5B6.5（原子百分数，下同）合金的非晶形成能力和快淬薄带的晶化温度，经过710℃晶化处理4min后，快淬薄带的晶粒细小均匀，从而显著提高了快淬薄带的磁性能。三维原子探针（Three-Dimensional Atom Probe，简称3DAP）分析结果表明，含Nb快淬薄带晶化后，在晶界形成了Nb-Fe-B偏聚物，抑制了晶粒长大，细化了晶粒，进而使晶粒间交换耦合作用增强，提高了合金的磁性能。
添加Nb可提高（Nd0.9Dy0.1）9.5Fe79Co5B6.5（原子百分数，下同）合金的非晶形成能力和快淬薄带的晶化温度，经过710℃晶化处理4min后，快淬薄带的晶粒细小均匀，从而显著提高了快淬薄带的磁性能。三维原子探针（Three-Dimensional Atom Probe，简称3DAP）分析结果表明，含Nb快淬薄带晶化后，在晶界形成了Nb-Fe-B偏聚物，抑制了晶粒长大，细化了晶粒，进而使晶粒间交换耦合作用增强，提高了合金的磁性能。
2007, 36(5):835-837.
Abstract:
LiFePO4/C composition cathode was synthesized by a method of in-situ carbon coating. The influence of ambient temperature on the capacity of LiFePO4/C was investigated. The Arrhenius relationship between capacity and temperature was observed by linear fit and deduced. Temperature dependence of its electrochemical characteristic was evaluated by using AC impedance spectroscopy. A new equivalent circuit based on the charge and mass transfer control process in electrode was suggested to fit the obtained AC impedance spectra. The tendency of every element in equivalent circuit obtained by Zview fitting system was used to interpret the temperature dependence of capacity for LiFePO4/C composition cathode.
LiFePO4/C composition cathode was synthesized by a method of in-situ carbon coating. The influence of ambient temperature on the capacity of LiFePO4/C was investigated. The Arrhenius relationship between capacity and temperature was observed by linear fit and deduced. Temperature dependence of its electrochemical characteristic was evaluated by using AC impedance spectroscopy. A new equivalent circuit based on the charge and mass transfer control process in electrode was suggested to fit the obtained AC impedance spectra. The tendency of every element in equivalent circuit obtained by Zview fitting system was used to interpret the temperature dependence of capacity for LiFePO4/C composition cathode.
2007, 36(5):838-841.
Abstract:
The silver base materials containing MgF2 were synthesized by powder metallurgy method. The micro-structures were studied by X-ray diffraction, metallograph and thermal analysis. The hardness, conductance, density and the friction coefficient of materials were tested. The results indicate that the Ag and MgF2 were combined in an atom range with a relative density over 98%, and the conductance of Ag samples added with CaF2 declined obviously; and the grains became thinner obviously. The hardness of material did not obviously increase and and the fi-iction coefficient to Ag and Cu did not obviously decline. In a word, the MgF2 can not be used as the additives of the solid self-lubricating materials.
The silver base materials containing MgF2 were synthesized by powder metallurgy method. The micro-structures were studied by X-ray diffraction, metallograph and thermal analysis. The hardness, conductance, density and the friction coefficient of materials were tested. The results indicate that the Ag and MgF2 were combined in an atom range with a relative density over 98%, and the conductance of Ag samples added with CaF2 declined obviously; and the grains became thinner obviously. The hardness of material did not obviously increase and and the fi-iction coefficient to Ag and Cu did not obviously decline. In a word, the MgF2 can not be used as the additives of the solid self-lubricating materials.
2007, 36(5):842-845.
Abstract:
A spectroscopic measuring system was described and developed to analyze the time-varying optical spectra of electrical contacts. A simulaton system of contact life, a monochromator, a photomultiplier tube (CR114) and a four channel digital storage oscillograph are used as optical detectors, so that the precise and quick measurements can be made for the spectrums with tim. At the same time, arc voltage waveform is measured for the breaking arc at the source voltage E of 24 V and the closed contact current I of 18 A. It is shown that this system can be applied to analyse the electric arc light and voltage for spectrums, and the dynamic characteristic of the breaking arc on Ag and Ag/MeO electric contacts.
A spectroscopic measuring system was described and developed to analyze the time-varying optical spectra of electrical contacts. A simulaton system of contact life, a monochromator, a photomultiplier tube (CR114) and a four channel digital storage oscillograph are used as optical detectors, so that the precise and quick measurements can be made for the spectrums with tim. At the same time, arc voltage waveform is measured for the breaking arc at the source voltage E of 24 V and the closed contact current I of 18 A. It is shown that this system can be applied to analyse the electric arc light and voltage for spectrums, and the dynamic characteristic of the breaking arc on Ag and Ag/MeO electric contacts.
2007, 36(5):846-848.
Abstract:
利用固体与分子经验电子理论计算了Ti2AlNb基合金中外来原子W的不同占位比引起基体电子结构的变化，分析了价电子结构参数nA，σ和P的变化及描述原子状态的特征参数nT，nc,n的变化，讨论了W存不同占位比情况下的价电子结构对合金性能的影响。
利用固体与分子经验电子理论计算了Ti2AlNb基合金中外来原子W的不同占位比引起基体电子结构的变化，分析了价电子结构参数nA，σ和P的变化及描述原子状态的特征参数nT，nc,n的变化，讨论了W存不同占位比情况下的价电子结构对合金性能的影响。
22 Mathematical Model of Body Force in Electromagnetic Purification at Magnetic Field of High Frequency
2007, 36(5):849-852.
Abstract:
鉴于液态金属内部电磁力分布对电磁净化效果的影响，提出了高频电磁场电磁净化技术中电磁体积力的数学模型，并具体分析了不同电力参数和实验参数下金属熔体内部电磁体积力的分布规律。研究表明，增加磁感应强度能够有效地增大熔体内部电磁体积力，从而提高净化效率；增加电源频率能够有效地改变熔体内部电磁体积力的分布规律，增大熔体表面的电磁体积力，但是随着电源频率的增大将减小电磁力在金属内部的作用区域，使得电磁净化的有效作用范围减小；在一定磁感应强度下，熔体内部某一深度处的电磁体积力随着频率的增加先增大后减小，当频率满足f=1（4πσμχ^2）时，该处的电磁体积力取得最大值。
鉴于液态金属内部电磁力分布对电磁净化效果的影响，提出了高频电磁场电磁净化技术中电磁体积力的数学模型，并具体分析了不同电力参数和实验参数下金属熔体内部电磁体积力的分布规律。研究表明，增加磁感应强度能够有效地增大熔体内部电磁体积力，从而提高净化效率；增加电源频率能够有效地改变熔体内部电磁体积力的分布规律，增大熔体表面的电磁体积力，但是随着电源频率的增大将减小电磁力在金属内部的作用区域，使得电磁净化的有效作用范围减小；在一定磁感应强度下，熔体内部某一深度处的电磁体积力随着频率的增加先增大后减小，当频率满足f=1（4πσμχ^2）时，该处的电磁体积力取得最大值。
2007, 36(5):853-856.
Abstract:
利用放电等离子烧结（SPS）技术，原位制备Ti2AlC／TiAl和Ti2AlC／TiAl（Nb，B）复合材料，并研究其在900℃和1000℃的高温氧化性能。研究发现，掺加Nb，B后复合材料的抗氧化性能明显提高，1000℃氧化30h时氧化层厚度为50μm～60μm，未掺入Nb，B时其厚度约为170μm。在氧化层和复合材料交界处结构疏松出现许多孔洞，Nb原子在高温时向表面层富集使复合材料抗氧化性能提高，富Nb层的存在即可以阻挡氧原子的继续渗入，又可以作为扩散障，减少Kirkendall效应；加入B后，组织明显细化，氧化反应初始阶段氧化物的形核增多。
利用放电等离子烧结（SPS）技术，原位制备Ti2AlC／TiAl和Ti2AlC／TiAl（Nb，B）复合材料，并研究其在900℃和1000℃的高温氧化性能。研究发现，掺加Nb，B后复合材料的抗氧化性能明显提高，1000℃氧化30h时氧化层厚度为50μm～60μm，未掺入Nb，B时其厚度约为170μm。在氧化层和复合材料交界处结构疏松出现许多孔洞，Nb原子在高温时向表面层富集使复合材料抗氧化性能提高，富Nb层的存在即可以阻挡氧原子的继续渗入，又可以作为扩散障，减少Kirkendall效应；加入B后，组织明显细化，氧化反应初始阶段氧化物的形核增多。
2007, 36(5):857-861.
Abstract:
TiN films were deposited onto the NiTi shape memory alloys by an arc ion plating technique. The phase identification and surface characteristics of the specimens were successively performed and tested by X-ray diffraction, scanning electron microscope and atom force microscopy. We investigated and compared compatibility and corrosion properties of NiTi alloys in vitro blood with and without TiN film. Experimental results indicated that the TiN film had improved the blood compatibility and corrosion resistance properties of NiTi alloy, and the release rate of Ni ions was reduced about one magnitude after plated TiN film; the thicker the film was, the more the properties improved.
TiN films were deposited onto the NiTi shape memory alloys by an arc ion plating technique. The phase identification and surface characteristics of the specimens were successively performed and tested by X-ray diffraction, scanning electron microscope and atom force microscopy. We investigated and compared compatibility and corrosion properties of NiTi alloys in vitro blood with and without TiN film. Experimental results indicated that the TiN film had improved the blood compatibility and corrosion resistance properties of NiTi alloy, and the release rate of Ni ions was reduced about one magnitude after plated TiN film; the thicker the film was, the more the properties improved.
2007, 36(5):862-864.
Abstract:
研究基片斜切角度对YBCO薄膜微观结构及超导电性能的影响。采用脉冲激光沉积（PLD）法在0°～6°斜切（001）SrTiO3基片上制备了具有c取向的YBCO薄膜。用XRD和TEM对薄膜微观结构进行了分析，用标准四引线法测定薄膜电阻．温度关系，从而确定薄膜的超导电性能。结果表明，随斜切角度的增大，薄膜晶体质量下降，晶格弯曲畸变程度增大，超导临界转变温度降低，转变宽度增大。
研究基片斜切角度对YBCO薄膜微观结构及超导电性能的影响。采用脉冲激光沉积（PLD）法在0°～6°斜切（001）SrTiO3基片上制备了具有c取向的YBCO薄膜。用XRD和TEM对薄膜微观结构进行了分析，用标准四引线法测定薄膜电阻．温度关系，从而确定薄膜的超导电性能。结果表明，随斜切角度的增大，薄膜晶体质量下降，晶格弯曲畸变程度增大，超导临界转变温度降低，转变宽度增大。
2007, 36(5):865-868.
Abstract:
以自蔓延高温合成（SHS）的Ti2AlC粉体为原料，利用放电等离子烧结技术（SPS）研究了Ti2AlC陶瓷的烧结制备。结果表明：烧结温度1250℃，压力20MPa，真空烧结，保温5min，可获得相对密度98．6％，维氏硬度为4．3GPa的致密烧结块体；烧结样品的维氏硬度随烧结温度升高而增大，但高于1250℃后随温度升高反而减小，SPS方法烧结Ti2AlC陶瓷的最佳温度为1250℃，当烧结温度≥1350℃时Ti2AlC分解；SEM分析表明，SPS技术烧结制备的Ti2AlC陶瓷片层尺寸随烧结温度的升高而增大。
以自蔓延高温合成（SHS）的Ti2AlC粉体为原料，利用放电等离子烧结技术（SPS）研究了Ti2AlC陶瓷的烧结制备。结果表明：烧结温度1250℃，压力20MPa，真空烧结，保温5min，可获得相对密度98．6％，维氏硬度为4．3GPa的致密烧结块体；烧结样品的维氏硬度随烧结温度升高而增大，但高于1250℃后随温度升高反而减小，SPS方法烧结Ti2AlC陶瓷的最佳温度为1250℃，当烧结温度≥1350℃时Ti2AlC分解；SEM分析表明，SPS技术烧结制备的Ti2AlC陶瓷片层尺寸随烧结温度的升高而增大。
2007, 36(5):869-873.
Abstract:
采用双辉等离子渗金属技术在Ti-6Al-4V表面形成均匀致密连续的渗铌合金层。将未渗铌和渗铌的Ti-6Al-4V试样分别在700℃，800℃，900℃进行100h的高温氧化实验，采用XRD，SEM及EDX对试样在900℃氧化100h后的氧化层的相组成、截面形貌及成分分布进行分析，初步探讨Ti-6Al-4V表面渗铌后的抗氧化性能及氧化机理。结果表明：渗铌后的Ti-6Al-4V合金氧化速率常数降低了1个数量级，氧化激活能提高，抗氧化性能明显改善。
采用双辉等离子渗金属技术在Ti-6Al-4V表面形成均匀致密连续的渗铌合金层。将未渗铌和渗铌的Ti-6Al-4V试样分别在700℃，800℃，900℃进行100h的高温氧化实验，采用XRD，SEM及EDX对试样在900℃氧化100h后的氧化层的相组成、截面形貌及成分分布进行分析，初步探讨Ti-6Al-4V表面渗铌后的抗氧化性能及氧化机理。结果表明：渗铌后的Ti-6Al-4V合金氧化速率常数降低了1个数量级，氧化激活能提高，抗氧化性能明显改善。
2007, 36(5):874-878.
Abstract:
Three kinds of Ti-based PbO2 electrodes with or without SnO2+Sb2O3 interlayers were prepared by the thermal decomposition of Pb(NO3)2 solution and applied as anodes to simulate the electrolytic degradation process of phenol in aqueous solution. The experimental results show that the cell voltages for the anodes with the interlayers are lower than that without the interlayers. There are little differences in the removal rate of phenol, the COD values and the instantaneous current efficiency for the three kinds of electrode. The phenol removal rate reaches 99.2% after degradation process for 3.0 h, and the COD value declines to15.7% after degradation process for 6.5 h for the Ti/SnO2+Sb2O3/PbO2 electrode obtained by a polymeric precursor method as an anode. The instantaneous current efficiencies of electrolysis process for the three kinds of electrodes decrease with increasing the electrolysis time. The electrocatalytic activity and the accelerated lifetime were assessed by cyclic voltammetry and accelerated life tests for the three kinds of anodes. It has been found that the accelerated lifetime and electrocatalytic activity of the electrodes with SnO2+Sb2O3 interlayer are improved obviously.
Three kinds of Ti-based PbO2 electrodes with or without SnO2+Sb2O3 interlayers were prepared by the thermal decomposition of Pb(NO3)2 solution and applied as anodes to simulate the electrolytic degradation process of phenol in aqueous solution. The experimental results show that the cell voltages for the anodes with the interlayers are lower than that without the interlayers. There are little differences in the removal rate of phenol, the COD values and the instantaneous current efficiency for the three kinds of electrode. The phenol removal rate reaches 99.2% after degradation process for 3.0 h, and the COD value declines to15.7% after degradation process for 6.5 h for the Ti/SnO2+Sb2O3/PbO2 electrode obtained by a polymeric precursor method as an anode. The instantaneous current efficiencies of electrolysis process for the three kinds of electrodes decrease with increasing the electrolysis time. The electrocatalytic activity and the accelerated lifetime were assessed by cyclic voltammetry and accelerated life tests for the three kinds of anodes. It has been found that the accelerated lifetime and electrocatalytic activity of the electrodes with SnO2+Sb2O3 interlayer are improved obviously.
2007, 36(5):879-883.
Abstract:
通过测定热膨胀系数研究了热处理工艺对NiTi合金负热膨胀（NTE）行为的影响，并采用XRD和TEM分析对其机理进行了探讨。研究表明：360℃，130h约束时效时，随着外加应力的增加，NiTi合金的负热膨胀系数先增后减，在250MPa时可获得峰值-87．0×10^-6K^-1；时效温度升高或高温下时效时间延长，其NTE行为变差。母相中Ti3Ni4相定向析出所形成的内应力场有效控制了相变的发生并促使产生体积变化和双程形状记忆效应，二者的联合作用导致了NTE行为的产生。
通过测定热膨胀系数研究了热处理工艺对NiTi合金负热膨胀（NTE）行为的影响，并采用XRD和TEM分析对其机理进行了探讨。研究表明：360℃，130h约束时效时，随着外加应力的增加，NiTi合金的负热膨胀系数先增后减，在250MPa时可获得峰值-87．0×10^-6K^-1；时效温度升高或高温下时效时间延长，其NTE行为变差。母相中Ti3Ni4相定向析出所形成的内应力场有效控制了相变的发生并促使产生体积变化和双程形状记忆效应，二者的联合作用导致了NTE行为的产生。
2007, 36(5):884-887.
Abstract:
在高铌TiAl基金属间化合物的基础上添加W，B，Y合金元素，熔炼了5种合金，研究了这5种合金在900℃静止空气中的断续氧化行为。1000h氧化后的结果表明：含0．1％（原子分数，下同）的Y使合金的抗氧化性有所提高，促进合金形成了以Al2O3为主的连续致密氧化层；存高铌含Y合金中添加W，B2种合金元素则导致基体发生了严重的内氧化，使合金的抗氧化性能降低。
在高铌TiAl基金属间化合物的基础上添加W，B，Y合金元素，熔炼了5种合金，研究了这5种合金在900℃静止空气中的断续氧化行为。1000h氧化后的结果表明：含0．1％（原子分数，下同）的Y使合金的抗氧化性有所提高，促进合金形成了以Al2O3为主的连续致密氧化层；存高铌含Y合金中添加W，B2种合金元素则导致基体发生了严重的内氧化，使合金的抗氧化性能降低。
2007, 36(5):888-891.
Abstract:
为了改善93W-4．9Ni-2．1Fe合金的力学性能，对MA制备93W-4．9Ni-2．1Fe超细预合金粉末的烧结特性进行了研究。采用比表面吸附法测算了预合金粉末粒度，用X射线衍射仪对粉末晶粒尺寸进行测算，扫描电镜观察球磨粉末和试样拉伸断口的形貌，用金相显微镜对试样显微组织进行观察。结果表明：球磨50h后可得到粒度为0．29gm、晶粒尺寸为25．5nm、各元素分布均匀的超细93W-4．9Ni-2．1Fe预合金粉末：球磨50h的预合金粉末在1480℃烧结90min压坯，钨晶粒呈球形或近球形；合金抗拉强度、延伸率和相对密度分别为1025．4MPa，26．47％和99．45％，合金呈钨晶粒的穿晶解理断裂和粘结相的延性撕裂。
为了改善93W-4．9Ni-2．1Fe合金的力学性能，对MA制备93W-4．9Ni-2．1Fe超细预合金粉末的烧结特性进行了研究。采用比表面吸附法测算了预合金粉末粒度，用X射线衍射仪对粉末晶粒尺寸进行测算，扫描电镜观察球磨粉末和试样拉伸断口的形貌，用金相显微镜对试样显微组织进行观察。结果表明：球磨50h后可得到粒度为0．29gm、晶粒尺寸为25．5nm、各元素分布均匀的超细93W-4．9Ni-2．1Fe预合金粉末：球磨50h的预合金粉末在1480℃烧结90min压坯，钨晶粒呈球形或近球形；合金抗拉强度、延伸率和相对密度分别为1025．4MPa，26．47％和99．45％，合金呈钨晶粒的穿晶解理断裂和粘结相的延性撕裂。
2007, 36(5):892-895.
Abstract:
Tungsten alloy scraps are considered as the second tungsten resource to recycle. The plasticity of recycled tungsten alloy has been deeply investigated in this paper. The study indicated that Ni and Fe powders of given amounts were added and mixed to the recycled powder can increase the plasticity of recycled alloy greatly. After vacuum heat treatment, the plastic behavior of recycled tungsten alloy was improved. For example, the elongation increased by about 43.4% and the cross section contraction ratio increased by about 33.9%.
Tungsten alloy scraps are considered as the second tungsten resource to recycle. The plasticity of recycled tungsten alloy has been deeply investigated in this paper. The study indicated that Ni and Fe powders of given amounts were added and mixed to the recycled powder can increase the plasticity of recycled alloy greatly. After vacuum heat treatment, the plastic behavior of recycled tungsten alloy was improved. For example, the elongation increased by about 43.4% and the cross section contraction ratio increased by about 33.9%.
2007, 36(5):896-898.
Abstract:
The film of La-Ni alloy was prepared by electrodepositing method in an aqueous solution. The structures of film before and after charge-discharge cycles were measured by XRD and the surface feature was observed by SEM. The electrochemical hydrogen storage performance of the film was studied by cyclic voltammetry and electrochemical impedance spectrum. The results showed that the film had a good electrochemical activity, unnecessary for an activation procedure and the maximum electrochemical capacity was 156 mAh/g.
The film of La-Ni alloy was prepared by electrodepositing method in an aqueous solution. The structures of film before and after charge-discharge cycles were measured by XRD and the surface feature was observed by SEM. The electrochemical hydrogen storage performance of the film was studied by cyclic voltammetry and electrochemical impedance spectrum. The results showed that the film had a good electrochemical activity, unnecessary for an activation procedure and the maximum electrochemical capacity was 156 mAh/g.
2007, 36(5):899-902.
Abstract:
采用溶胶-凝胶法制备了纳米晶La0.8Sr0.2FeO3。X射线衍射表明：该样品为正交晶系钙钛矿结构，其平均粒径约为31nm。将La0.8Sr0.2FeO3纳米晶粉体与聚乙烯醇PVA混合固化，然后在400℃下分别退火20min和120min。固化退火120min的元器件电阻随乙醇浓度的增加而增加，元器件具有P型半导体特性。而固化退火20min的元器件电阻随乙醇浓度的增加而减小，该元器件具有n型半导体特点。固化退火120min的La0．8Sr0．2FeO3元器件的气敏灵敏度S=Rg／Ra在80℃下高达100，低工作温度、高灵敏度特性对应用有益。发现La0.8Sr0.2FeO3元器件的电阻R和乙醇浓度C只在较低温区符合指数关系（R≈KC^α）。
采用溶胶-凝胶法制备了纳米晶La0.8Sr0.2FeO3。X射线衍射表明：该样品为正交晶系钙钛矿结构，其平均粒径约为31nm。将La0.8Sr0.2FeO3纳米晶粉体与聚乙烯醇PVA混合固化，然后在400℃下分别退火20min和120min。固化退火120min的元器件电阻随乙醇浓度的增加而增加，元器件具有P型半导体特性。而固化退火20min的元器件电阻随乙醇浓度的增加而减小，该元器件具有n型半导体特点。固化退火120min的La0．8Sr0．2FeO3元器件的气敏灵敏度S=Rg／Ra在80℃下高达100，低工作温度、高灵敏度特性对应用有益。发现La0.8Sr0.2FeO3元器件的电阻R和乙醇浓度C只在较低温区符合指数关系（R≈KC^α）。
2007, 36(5):903-906.
Abstract:
采用固相反应法制备了样品La0.67Sr0.33-xNaxMnO3（x=0．05，0．10，0．15，0．20，0．25，0．33）。通过实验测出了样品的X射线衍射谱图、M-T曲线、p-T曲线和MR-T曲线，研究了Sr位掺Na对La0.67Sr0.33MnO3的晶格结构和磁电特性的影响。结果表明，样品呈菱面体结构，当x≥0．20时，Mn^3＋／Mn^4＋〈1，体系在反铁磁态，但实验中所有样品表现为顺磁-铁磁相变伴随绝缘体．金属相变；随X增加，巨磁电阻MR增大，Tc降低，当x=0．33时，在室温区获得了很大的磁电阻MR=241％。
采用固相反应法制备了样品La0.67Sr0.33-xNaxMnO3（x=0．05，0．10，0．15，0．20，0．25，0．33）。通过实验测出了样品的X射线衍射谱图、M-T曲线、p-T曲线和MR-T曲线，研究了Sr位掺Na对La0.67Sr0.33MnO3的晶格结构和磁电特性的影响。结果表明，样品呈菱面体结构，当x≥0．20时，Mn^3＋／Mn^4＋〈1，体系在反铁磁态，但实验中所有样品表现为顺磁-铁磁相变伴随绝缘体．金属相变；随X增加，巨磁电阻MR增大，Tc降低，当x=0．33时，在室温区获得了很大的磁电阻MR=241％。
2007, 36(5):907-909.
Abstract:
采用放电等离子烧结技术（SPS）制备La-Mg-Ni储氢合金，以La0.7Mg0．3Ni2.5Co0.5合金为例，探究最佳的工艺制度。结果表明：当烧结温度为800℃时，合金为多相结构，包括（La，Mg）Ni3相、（La，Mg）2Ni7相、Mg2Ni相和微量的Co2Mg相；在该温度下，合金的最大放电容量达到最大值359mAh／g，同时表现出最好的放电平台特性。
采用放电等离子烧结技术（SPS）制备La-Mg-Ni储氢合金，以La0.7Mg0．3Ni2.5Co0.5合金为例，探究最佳的工艺制度。结果表明：当烧结温度为800℃时，合金为多相结构，包括（La，Mg）Ni3相、（La，Mg）2Ni7相、Mg2Ni相和微量的Co2Mg相；在该温度下，合金的最大放电容量达到最大值359mAh／g，同时表现出最好的放电平台特性。
2007, 36(5):910-914.
Abstract:
在研究镁合金板材熔铸及加工工艺的基础上，以AZ31B镁合金为材料，以优化组织性能为目标，通过控制轧制温度、压下制度、控温轧制和退火制度，轧制出σb≥280MPa，σo.2≥160MPa，d≥16％的镁合金板材，所轧制出的板材成功地得到实际应用，并对工艺制度的合理性从理论上进行了分析。
在研究镁合金板材熔铸及加工工艺的基础上，以AZ31B镁合金为材料，以优化组织性能为目标，通过控制轧制温度、压下制度、控温轧制和退火制度，轧制出σb≥280MPa，σo.2≥160MPa，d≥16％的镁合金板材，所轧制出的板材成功地得到实际应用，并对工艺制度的合理性从理论上进行了分析。
2007, 36(5):915-919.
Abstract:
The setup and principle od damper cooling tube (DCT) process to prepare the semisolid slurry of A356 aluminum alloy were introduced in different pouring temperatures. The results of measured and calculated grain size and shape factor in castings microstructure show that they are directly related to the pouring temperature, the lower the pouring temperature, the smaller the grain size and shape factor, due to the formation of stray nucleus and the cooling and stir of DCT. The semisolid slurry or billet produced by DCT processis are suitable for the semisolid processing owing to the fine grain size and spherical primary particles.
The setup and principle od damper cooling tube (DCT) process to prepare the semisolid slurry of A356 aluminum alloy were introduced in different pouring temperatures. The results of measured and calculated grain size and shape factor in castings microstructure show that they are directly related to the pouring temperature, the lower the pouring temperature, the smaller the grain size and shape factor, due to the formation of stray nucleus and the cooling and stir of DCT. The semisolid slurry or billet produced by DCT processis are suitable for the semisolid processing owing to the fine grain size and spherical primary particles.
2007, 36(5):920-923.
Abstract:
High purity alumina/stainless steel joints were produced by activated molybdenum -manganese route using 72Ag28Cu solder. The microstructure and elemental distribution of metallized ceramic were analyzed, and the mechanism of metallization was discussed. Influences of the metallizing technologic conditions, Ni plating and subsequent annealing on the joint shear strength were investigated. The results show that both glassy phases migration and chemical reaction act the key roles for activated Mo-Mn metallizing, but sintering of the metallized layer acts the secondary role, and the main direction of glass migration is from the metallzed layer to the ceramic matrix. The maximum of the joint shear strength under the optimized conditions reaches 115 MPa, and the average strength is over 97 MPa. A thin Ni coating will prevent the metallized layer from being wetted by the solder in resulting avoiding the erosion of the layer by the solder. The annealing after plating could improve markedly the strength of the ioints.
High purity alumina/stainless steel joints were produced by activated molybdenum -manganese route using 72Ag28Cu solder. The microstructure and elemental distribution of metallized ceramic were analyzed, and the mechanism of metallization was discussed. Influences of the metallizing technologic conditions, Ni plating and subsequent annealing on the joint shear strength were investigated. The results show that both glassy phases migration and chemical reaction act the key roles for activated Mo-Mn metallizing, but sintering of the metallized layer acts the secondary role, and the main direction of glass migration is from the metallzed layer to the ceramic matrix. The maximum of the joint shear strength under the optimized conditions reaches 115 MPa, and the average strength is over 97 MPa. A thin Ni coating will prevent the metallized layer from being wetted by the solder in resulting avoiding the erosion of the layer by the solder. The annealing after plating could improve markedly the strength of the ioints.
40 Rapid Solidification Features of Ag-10Ni Immiscible Alloy by Ultrasonic Arc Spray Gas Atomization
2007, 36(5):924-928.
Abstract:
采用超音速电弧喷射气雾化制粉设备制备了难固溶Ag-10Ni合金粉末。研究了粉末粒度分布、形貌及凝固组特征，并对雾化熔滴的冷却速率及过冷度、凝固组织的凝固次序、形成机制进行了分析。结果表明：粉末分散性好、粒度主要集中在20pm～45μm、平均粒度32μm、形貌主要为球形和近球形；粉末颗粒凝固组织为富Ag基体＋弥散分布于基体中的细Ni相＋位于芯部的大直径初晶富Ni相，在大直径初晶富Ni相中弥散分布析出Ag相；富Ag基体的凝固组织为树枝晶组织，小颗粒粉末（〈20μm）枝晶间距小于0．2μm。
采用超音速电弧喷射气雾化制粉设备制备了难固溶Ag-10Ni合金粉末。研究了粉末粒度分布、形貌及凝固组特征，并对雾化熔滴的冷却速率及过冷度、凝固组织的凝固次序、形成机制进行了分析。结果表明：粉末分散性好、粒度主要集中在20pm～45μm、平均粒度32μm、形貌主要为球形和近球形；粉末颗粒凝固组织为富Ag基体＋弥散分布于基体中的细Ni相＋位于芯部的大直径初晶富Ni相，在大直径初晶富Ni相中弥散分布析出Ag相；富Ag基体的凝固组织为树枝晶组织，小颗粒粉末（〈20μm）枝晶间距小于0．2μm。
2007, 36(5):929-932.
Abstract:
The nano-crystalline CuCr25 alloys have been prepared and the breakdown experiments have been done in vacuum room. The traces of cathode spots on the surface of coarse-crystalline and nano-crystalline CuCr25 alloys have been observed using a scanning electron microscope (SEM). Experimental results show that the spot diffusion of coarse-crystalline CuCr25 cathode local iterative combustion or whole jumping move on the Cr phases with a weak voltage withstanding. But the spot diffusion of nanocrystallization of CuCr25 cathode exhibits quasi-continuous move, as one falls and another rises, due to the superior condition for electron emission, and the breakdown phase distributing on the whole cathode surface.
The nano-crystalline CuCr25 alloys have been prepared and the breakdown experiments have been done in vacuum room. The traces of cathode spots on the surface of coarse-crystalline and nano-crystalline CuCr25 alloys have been observed using a scanning electron microscope (SEM). Experimental results show that the spot diffusion of coarse-crystalline CuCr25 cathode local iterative combustion or whole jumping move on the Cr phases with a weak voltage withstanding. But the spot diffusion of nanocrystallization of CuCr25 cathode exhibits quasi-continuous move, as one falls and another rises, due to the superior condition for electron emission, and the breakdown phase distributing on the whole cathode surface.
42 Diamond Films by CVD and High Rate Polishing at Low Temperature with Partially Molten Ce-Fe Alloy
2007, 36(5):933-936.
Abstract:
采用溶碳活性很高的稀土金属Ce和过渡金属Fe熔炼出Ce-7％Fe（原子分数，下同）合金，利用该合金对CVD金刚石膜进行热化学抛光。结果表明：Ce-7％Fe合金在592℃就可以抛光金刚石膜，比报道的稀土抛光温度要低200℃以上；在680℃抛光3h表面粗糙度Ra值由原来的5．95μm降低到0．69μm，抛光效率高达30μm／h；SEM观察表明，抛光使膜的表面光洁度有明显提高；经拉曼光谱检测，抛光没有对金刚石膜造成任何污染。
采用溶碳活性很高的稀土金属Ce和过渡金属Fe熔炼出Ce-7％Fe（原子分数，下同）合金，利用该合金对CVD金刚石膜进行热化学抛光。结果表明：Ce-7％Fe合金在592℃就可以抛光金刚石膜，比报道的稀土抛光温度要低200℃以上；在680℃抛光3h表面粗糙度Ra值由原来的5．95μm降低到0．69μm，抛光效率高达30μm／h；SEM观察表明，抛光使膜的表面光洁度有明显提高；经拉曼光谱检测，抛光没有对金刚石膜造成任何污染。
2007, 36(5):937-940.
Abstract:
采用电化学沉积法，在Cu基片上制备出了平均晶粒尺寸为3nm的纳米晶α-Mn通过对其在不同温度下真空退火，得到具有不同平均晶粒尺寸的纳米晶α-Mn系列样品。同时分析了电沉积、热处理条件对结构的影响，研究了结构与力学性能的关系。结果表明，随晶粒尺寸的减小，纳米晶α-Mn的力学性能表现出正Hall—Petch关系和反Hall—Petch关系；当晶粒小于临界晶粒尺寸42nm时，正Hall—Petch关系转变为反Hall—Petch关系。
采用电化学沉积法，在Cu基片上制备出了平均晶粒尺寸为3nm的纳米晶α-Mn通过对其在不同温度下真空退火，得到具有不同平均晶粒尺寸的纳米晶α-Mn系列样品。同时分析了电沉积、热处理条件对结构的影响，研究了结构与力学性能的关系。结果表明，随晶粒尺寸的减小，纳米晶α-Mn的力学性能表现出正Hall—Petch关系和反Hall—Petch关系；当晶粒小于临界晶粒尺寸42nm时，正Hall—Petch关系转变为反Hall—Petch关系。
