Volume 0,Issue 6,2003 Table of Contents
2003(6):401-406.
Abstract:
With the development of numerical technique and computer technology, the numerical modeling of the solidification process is changing from macro to micro modeling. By micro modeling not only the solidified microstructure of materials can be predicted, but also the accurate information of latent heat releasing can be provided for the macro modeling. The complete coupling of macro and micro modeling can result in a more accurate prediction for the solidification process of casting alloys. In the paper the state of art of the microstructure simulation was given in order to describe the main methods of micro modeling, such as deterministic, stochastic and phase field modeling, etc. Because of the complexity of numerical simulation of the solidification microstructure, it is necessary to study deeply the microstructure simulation, which would be the important research orientation in the field of computational materials science. Finally, the existent problem and the future developing orientation were analyzed.
With the development of numerical technique and computer technology, the numerical modeling of the solidification process is changing from macro to micro modeling. By micro modeling not only the solidified microstructure of materials can be predicted, but also the accurate information of latent heat releasing can be provided for the macro modeling. The complete coupling of macro and micro modeling can result in a more accurate prediction for the solidification process of casting alloys. In the paper the state of art of the microstructure simulation was given in order to describe the main methods of micro modeling, such as deterministic, stochastic and phase field modeling, etc. Because of the complexity of numerical simulation of the solidification microstructure, it is necessary to study deeply the microstructure simulation, which would be the important research orientation in the field of computational materials science. Finally, the existent problem and the future developing orientation were analyzed.
2003(6):407-411.
Abstract:
Two kinds of cryomilling mills have been introduced. The current status of research of cryomilling has been briefly reviewed. The applications for nm scaled materials with high thermal stability are especially emphasized. The mechanism of alloying for cryomilling and the stability at elevated temperature are discussed. The future trend of cryomilling is presented.
Two kinds of cryomilling mills have been introduced. The current status of research of cryomilling has been briefly reviewed. The applications for nm scaled materials with high thermal stability are especially emphasized. The mechanism of alloying for cryomilling and the stability at elevated temperature are discussed. The future trend of cryomilling is presented.
2003(6):412-416.
Abstract:
On basis of the internet resources, The concept and the processing of DU metal were introduced, including the physical and chemical properties and their applications in variety of fields. Specially the structures and characters of DU penetrators were described in detail. The aftermath of radiative pllution brought by DU on the warfield and force crew was discussed thoroughly. The unsolved problems of DU munitions and its development prospect were also presented.
On basis of the internet resources, The concept and the processing of DU metal were introduced, including the physical and chemical properties and their applications in variety of fields. Specially the structures and characters of DU penetrators were described in detail. The aftermath of radiative pllution brought by DU on the warfield and force crew was discussed thoroughly. The unsolved problems of DU munitions and its development prospect were also presented.
2003(6):417-419.
Abstract:
用扫描探针显微镜(SPM)研究了Zr—4合金在高压釜中经360℃高温水腐蚀后氧化膜中的显微组织和晶粒形貌。从氧化膜表面上观察到的晶粒在100nm～400nm之间，比从截面上观察到的大，说明氧化膜的晶粒在腐蚀过程中仍在不断长大。从离子轰击蚀刻后的氧化膜截面上，可以区分出由大角度晶界构成的柱状晶，以及在柱状晶中由小角度晶界构成的等轴晶。在三晶交界处，常常有明显的“凹陷”，这应是空位扩散凝聚后形成的空洞，尺度在几纳米至几十纳米间。在氧化膜的截面上，除了可观察到裂纹和空洞等缺陷外，在氧化膜／金属交界处，有时还可观察到片层状的氢化锆和显示不出晶界的非晶ZrO2。
用扫描探针显微镜(SPM)研究了Zr—4合金在高压釜中经360℃高温水腐蚀后氧化膜中的显微组织和晶粒形貌。从氧化膜表面上观察到的晶粒在100nm～400nm之间，比从截面上观察到的大，说明氧化膜的晶粒在腐蚀过程中仍在不断长大。从离子轰击蚀刻后的氧化膜截面上，可以区分出由大角度晶界构成的柱状晶，以及在柱状晶中由小角度晶界构成的等轴晶。在三晶交界处，常常有明显的“凹陷”，这应是空位扩散凝聚后形成的空洞，尺度在几纳米至几十纳米间。在氧化膜的截面上，除了可观察到裂纹和空洞等缺陷外，在氧化膜／金属交界处，有时还可观察到片层状的氢化锆和显示不出晶界的非晶ZrO2。
2003(6):420-423.
Abstract:
通过化学镀方法制备了Ni—B合金涂层。经DSC和XRD分析确认该合金涂层在0℃～500℃之间有3种相变发生，分别形成不同种类的镍硼化合物。涂层硬度也因镍硼化合物种类不同而变化。特定的处理工艺使涂层显微硬度(HV)高达15000MPa以上。用原子力显微镜(AFM)对涂层表面观察发现，不同热处理的该合金涂层表面形态不同。表面形态的差异对涂层的硬度有影响。特别是当涂层中出现粒径为40nm～100nm、高度为10nm～20nm的突起物时，涂层的硬度会大幅提高，并对硬度提高的机制作了讨论。
通过化学镀方法制备了Ni—B合金涂层。经DSC和XRD分析确认该合金涂层在0℃～500℃之间有3种相变发生，分别形成不同种类的镍硼化合物。涂层硬度也因镍硼化合物种类不同而变化。特定的处理工艺使涂层显微硬度(HV)高达15000MPa以上。用原子力显微镜(AFM)对涂层表面观察发现，不同热处理的该合金涂层表面形态不同。表面形态的差异对涂层的硬度有影响。特别是当涂层中出现粒径为40nm～100nm、高度为10nm～20nm的突起物时，涂层的硬度会大幅提高，并对硬度提高的机制作了讨论。
2003(6):424-427.
Abstract:
A ruthenium oxide coated activated carbon (RuO2/C) was synthesized as a new electrode material for aqueous electrolyte super capacitor. Some laboratory scale prototype capacitors were fabricated with the RuO2/actived carbon electrode material and tested in term of capacitance and high power discharge for their electrochemical performance.These composite super capacitors exhibited a satisfactory performance,such as the rated capacitance higher than 350 F/g,compared with that of single electrode material only.
A ruthenium oxide coated activated carbon (RuO2/C) was synthesized as a new electrode material for aqueous electrolyte super capacitor. Some laboratory scale prototype capacitors were fabricated with the RuO2/actived carbon electrode material and tested in term of capacitance and high power discharge for their electrochemical performance.These composite super capacitors exhibited a satisfactory performance,such as the rated capacitance higher than 350 F/g,compared with that of single electrode material only.
2003(6):428-431.
Abstract:
T1(Al2CuLi)相是Al-Li-Cu-Zr合金中的重要强化相.通过TEM在对T1相结构和形貌分析的基础上,构造了T1相的结构.T1相晶核以ABCBA的堆垛顺序,共由36个原子组成,其晶格常数a=0.495nm,c=0.933nm.与基体的位相关系为{0001}T1∥{111}α,<>T1∥<110>α.合金中铜原子的偏聚降低了基体的层错能,从而为T1相依赖扩散层错形核提供了有利条件.T1相长大依赖于原子扩散和台阶滑移,是一种长程扩散控制的台阶机制.
T1(Al2CuLi)相是Al-Li-Cu-Zr合金中的重要强化相.通过TEM在对T1相结构和形貌分析的基础上,构造了T1相的结构.T1相晶核以ABCBA的堆垛顺序,共由36个原子组成,其晶格常数a=0.495nm,c=0.933nm.与基体的位相关系为{0001}T1∥{111}α,<>T1∥<110>α.合金中铜原子的偏聚降低了基体的层错能,从而为T1相依赖扩散层错形核提供了有利条件.T1相长大依赖于原子扩散和台阶滑移,是一种长程扩散控制的台阶机制.
2003(6):432-435.
Abstract:
The bonding strength of hydroxyapatite(HA)/Ti FGM implants fabricated by powder metallurgy was investigated by means of the in vivo implanting in rabbits and the shear strength testing. It was shown that the HA/Ti FGM possess a good biocompatibility and osteoconductivity, and can be integrated with bone. After implanted for three months, the FGM implants and the new bone formed around became one bony body. The bonding strength between FGM implants and the surrounding bone tissues raises quickly with increasing the implanting time, and can reach 6.49MPa after implanted for three months, higher than that of dense pure HA or Ti implants. Fractography observations reveal that the fracture occurred in the new bone near the interface during the shear testing of HA/Ti FGM implants, which indicates that its interfacial bonding strength even exceeds the shear strength of new bone tissues.
The bonding strength of hydroxyapatite(HA)/Ti FGM implants fabricated by powder metallurgy was investigated by means of the in vivo implanting in rabbits and the shear strength testing. It was shown that the HA/Ti FGM possess a good biocompatibility and osteoconductivity, and can be integrated with bone. After implanted for three months, the FGM implants and the new bone formed around became one bony body. The bonding strength between FGM implants and the surrounding bone tissues raises quickly with increasing the implanting time, and can reach 6.49MPa after implanted for three months, higher than that of dense pure HA or Ti implants. Fractography observations reveal that the fracture occurred in the new bone near the interface during the shear testing of HA/Ti FGM implants, which indicates that its interfacial bonding strength even exceeds the shear strength of new bone tissues.
2003(6):436-439.
Abstract:
Stress corrosion crack (SCC) susceptibility of titanium alloy TC4 in methane and hydrochloric acid methane solution was studied by slow strain rate tensile test (SSRT), SEM analysis and metallography observation. The experimental results show that TC4 is possessed of SCC susceptibility in methanol solution, and addition of methanol solution to hydrochloric acid methanol solution can greatly improved the SCC susceptibility of TC4 alloy. SCC of TC4 in hydrochloric acid mdethanol solution originates from the bottom of the corrosion pits.
Stress corrosion crack (SCC) susceptibility of titanium alloy TC4 in methane and hydrochloric acid methane solution was studied by slow strain rate tensile test (SSRT), SEM analysis and metallography observation. The experimental results show that TC4 is possessed of SCC susceptibility in methanol solution, and addition of methanol solution to hydrochloric acid methanol solution can greatly improved the SCC susceptibility of TC4 alloy. SCC of TC4 in hydrochloric acid mdethanol solution originates from the bottom of the corrosion pits.
2003(6):440-442.
Abstract:
Effective and reasonable computational models are established to simulate the penetrating processes for the tungsten fiber reinforced tungsten alloy matrix composite penetrators and the tungsten alloy penetrators by the DYNA 3D finite element program. The simulation results are compared and verified by the penetrating experiments. The reason that the penetrating performance of the tungsten fiber reinforced tungsten alloy matrix composite penetrator is superior to that of the tungsten alloy penetrator is discussed.These results can provide reliable theory,computational models and experiment bases for further research.
Effective and reasonable computational models are established to simulate the penetrating processes for the tungsten fiber reinforced tungsten alloy matrix composite penetrators and the tungsten alloy penetrators by the DYNA 3D finite element program. The simulation results are compared and verified by the penetrating experiments. The reason that the penetrating performance of the tungsten fiber reinforced tungsten alloy matrix composite penetrator is superior to that of the tungsten alloy penetrator is discussed.These results can provide reliable theory,computational models and experiment bases for further research.
2003(6):443-446.
Abstract:
The superalloy melt is easily contaminated by the ceramic mold material because the melt is kept in it for long time for the traditional process. By the new electromagnetic soft contact confinement process, the superalloy melt is half suspended by electromagnetic pressure, so the contacting area and time between melt and magnetic mold decrease. Simultaneously, the contamination is decreased effectively. The new technique combines the electromangetic soft contact confinement with directional solidification process for manufacturing the near net shape turbine blade castings of superalloys. The effects of the magnetic mold material and the height and position of susceptor on the magnetic flux density distribution in the inductor were comprehensively investigated. In the experiment, two near net shape blade castings with directionally solidified microstucture are successfully obtained by the electromagnetic soft contact confinement process.
The superalloy melt is easily contaminated by the ceramic mold material because the melt is kept in it for long time for the traditional process. By the new electromagnetic soft contact confinement process, the superalloy melt is half suspended by electromagnetic pressure, so the contacting area and time between melt and magnetic mold decrease. Simultaneously, the contamination is decreased effectively. The new technique combines the electromangetic soft contact confinement with directional solidification process for manufacturing the near net shape turbine blade castings of superalloys. The effects of the magnetic mold material and the height and position of susceptor on the magnetic flux density distribution in the inductor were comprehensively investigated. In the experiment, two near net shape blade castings with directionally solidified microstucture are successfully obtained by the electromagnetic soft contact confinement process.
2003(6):447-450.
Abstract:
在Thermecmaster-Z型热加工模拟试验机上对TC6钛合金在温度800℃～1040℃,应变速率10s～50s、最大变形程度50%条件下的高温流动应力变化规律进行了研究,进而分析了变形参数对微观组织的影响。结果表明合适的工艺参数是变形温度为920℃～950℃,应变速率为1.0s-1～1×10-3s-1。在变形过程中,变形温度对α相体积分数有着显著影响,应变速率对α相体积分数影响不大,但对α相晶粒的形态有一定的影响。最后在分析变形温度、变形程度和应变速率对流动应力影响规律的基础上提出了1种本构关系模型,其拟合精度较高,为进行钛合金高温变形过程的数值模拟打下了较好的基础。
在Thermecmaster-Z型热加工模拟试验机上对TC6钛合金在温度800℃～1040℃,应变速率10s～50s、最大变形程度50%条件下的高温流动应力变化规律进行了研究,进而分析了变形参数对微观组织的影响。结果表明合适的工艺参数是变形温度为920℃～950℃,应变速率为1.0s-1～1×10-3s-1。在变形过程中,变形温度对α相体积分数有着显著影响,应变速率对α相体积分数影响不大,但对α相晶粒的形态有一定的影响。最后在分析变形温度、变形程度和应变速率对流动应力影响规律的基础上提出了1种本构关系模型,其拟合精度较高,为进行钛合金高温变形过程的数值模拟打下了较好的基础。
2003(6):451-455.
Abstract:
自生颗粒增强钛基复合材料中的TiC增强相，可分为初生TiC和共晶TiC，它们的形态、尺寸及形成机制均不尽相同。利用SEM、XRD、EDX等手段研究了钛合金中共晶TiC的形态及形成机制。合金中含碳量不同时，可能形成规则共晶或离异共晶。成分处于共晶点附近的合金，由于两相共生生长，β—Ti抑制了TiC的分枝，使TiC呈棒状或颗粒状，形成规则共晶。含碳量远低于共晶成分时易形成离异共晶，共晶反应发生在初生β—Ti枝晶的间隙中，多数共晶β—Ti依附于初生β—Ti生长，TiC与熔体接触增多，易分枝，而大量初生β—Ti的存在使TiC分枝受空间限制，只能在二维方向上分枝，从而促使羽毛状TiC的形成。Mo、Sn等合金元素的加入可使共晶TiC形态成为球团状。
自生颗粒增强钛基复合材料中的TiC增强相，可分为初生TiC和共晶TiC，它们的形态、尺寸及形成机制均不尽相同。利用SEM、XRD、EDX等手段研究了钛合金中共晶TiC的形态及形成机制。合金中含碳量不同时，可能形成规则共晶或离异共晶。成分处于共晶点附近的合金，由于两相共生生长，β—Ti抑制了TiC的分枝，使TiC呈棒状或颗粒状，形成规则共晶。含碳量远低于共晶成分时易形成离异共晶，共晶反应发生在初生β—Ti枝晶的间隙中，多数共晶β—Ti依附于初生β—Ti生长，TiC与熔体接触增多，易分枝，而大量初生β—Ti的存在使TiC分枝受空间限制，只能在二维方向上分枝，从而促使羽毛状TiC的形成。Mo、Sn等合金元素的加入可使共晶TiC形态成为球团状。
2003(6):456-459.
Abstract:
利用超临界CO2流体萃取技术从陶瓷注射成型坯体中萃取有机粘合剂。对陶瓷注射成型中所使用的有机载体组分进行研究，对陶瓷注射成型超临界CO2流体脱脂的工艺条件进行了探索，研究了不同萃取压力，温度及时间对萃取率和陶瓷坯体脱脂质量的影响。结果显示利用40％～50％(质量分数，下同)非极性分子有机物石蜡(PW)与30％～40％极性分子有机物聚丙烯(PP)及20％硬脂酸(SA)组成陶瓷注射成型熔体中的有机载体，在压力P=30MPa，温度T=58℃的超临界CO2流体中脱脂可在较短的时间内获得无缺陷的陶瓷注射成型生坯。
利用超临界CO2流体萃取技术从陶瓷注射成型坯体中萃取有机粘合剂。对陶瓷注射成型中所使用的有机载体组分进行研究，对陶瓷注射成型超临界CO2流体脱脂的工艺条件进行了探索，研究了不同萃取压力，温度及时间对萃取率和陶瓷坯体脱脂质量的影响。结果显示利用40％～50％(质量分数，下同)非极性分子有机物石蜡(PW)与30％～40％极性分子有机物聚丙烯(PP)及20％硬脂酸(SA)组成陶瓷注射成型熔体中的有机载体，在压力P=30MPa，温度T=58℃的超临界CO2流体中脱脂可在较短的时间内获得无缺陷的陶瓷注射成型生坯。
2003(6):460-463.
Abstract:
Hydrogen Decrepitation (HD) has been used as an efficient and economical method in producing coarse NdFeB powder. This article studied the effects of hydrogen on the Nd Dy Fe B magnets, such as HD powder oxidation and magnetic performance of sintered magnets. The results showed that the hydrogen accelerated the oxidation of the coarse Nd Dy Fe B powder after HD process, and the dehydrogenated powder had higher oxidation resistance, especially degassed at higher temperature, and the hydrogen dropped the sintering temperature of Nd Dy Fe B magnets. The effects of hydrogen may focus on that hydrogen bonds accelerate absorption of water from ambient air, and the defects caused by hydrogen induce oxygen diffusing more quickly. The magnets could be sintered at a lower temperature with un dehydrogenated HD powder, but had poorer orientation degree.
Hydrogen Decrepitation (HD) has been used as an efficient and economical method in producing coarse NdFeB powder. This article studied the effects of hydrogen on the Nd Dy Fe B magnets, such as HD powder oxidation and magnetic performance of sintered magnets. The results showed that the hydrogen accelerated the oxidation of the coarse Nd Dy Fe B powder after HD process, and the dehydrogenated powder had higher oxidation resistance, especially degassed at higher temperature, and the hydrogen dropped the sintering temperature of Nd Dy Fe B magnets. The effects of hydrogen may focus on that hydrogen bonds accelerate absorption of water from ambient air, and the defects caused by hydrogen induce oxygen diffusing more quickly. The magnets could be sintered at a lower temperature with un dehydrogenated HD powder, but had poorer orientation degree.
2003(6):464-467.
Abstract:
Some new magnetic properties would be produced during processing for the stainless steel fibers. The magnetic parameters had been obtained through a systemic testing and microstructure observation by XRD for the stainless steel fibers. The results showed that the change of composing phases, the internal stress and the microstructure had insignificant effects on the magnetic properties for the stainless steel fibers. It was important to optimize the processing parameters and to expend the application fields for the stainless steel fibers.
Some new magnetic properties would be produced during processing for the stainless steel fibers. The magnetic parameters had been obtained through a systemic testing and microstructure observation by XRD for the stainless steel fibers. The results showed that the change of composing phases, the internal stress and the microstructure had insignificant effects on the magnetic properties for the stainless steel fibers. It was important to optimize the processing parameters and to expend the application fields for the stainless steel fibers.
2003(6):468-470.
Abstract:
将水热合成引入到Pechini方法制得了尖晶石结构的锂离子电池正极材料LiMn2O4，此方法不但节省原料，而且工艺简单易行。讨论了煅烧温度、粒度和比表面积因素对LiMn2O4电化学性能的影响。结果表明：在煅烧温度为650℃时，晶化完全，粒子尺寸适中，初始容量为122mAh／g。
将水热合成引入到Pechini方法制得了尖晶石结构的锂离子电池正极材料LiMn2O4，此方法不但节省原料，而且工艺简单易行。讨论了煅烧温度、粒度和比表面积因素对LiMn2O4电化学性能的影响。结果表明：在煅烧温度为650℃时，晶化完全，粒子尺寸适中，初始容量为122mAh／g。
2003(6):471-474.
Abstract:
Viscosity of Al 16% Si alloys modified by Ce adding with different contents was studied. The results showed that the viscosity increased with the addition of Ce and their content. The variation of liquid structure and the relations between the liquid structure and the viscosity were discussed and analyzed for Al 16% Si alloys according to the variation of the hydrogen content, the solidification structure and the DSC curves.
Viscosity of Al 16% Si alloys modified by Ce adding with different contents was studied. The results showed that the viscosity increased with the addition of Ce and their content. The variation of liquid structure and the relations between the liquid structure and the viscosity were discussed and analyzed for Al 16% Si alloys according to the variation of the hydrogen content, the solidification structure and the DSC curves.
2003(6):475-477.
Abstract:
The burned resistant and reliability of initiating arc in GTAW for 1% CeO2 and 2% CeO2 tungsten bar have been compared in this research . It has been suggested that the tungsten bar with 1% CeO2 has a lower burned rate during manufacturing and better electrode performance in GTAW than the 2% CeO_2 tungsten bar .
The burned resistant and reliability of initiating arc in GTAW for 1% CeO2 and 2% CeO2 tungsten bar have been compared in this research . It has been suggested that the tungsten bar with 1% CeO2 has a lower burned rate during manufacturing and better electrode performance in GTAW than the 2% CeO_2 tungsten bar .
2003(6):478-480.
Abstract:
Mean and local residual stresses in Cu films and Ag films on 4Cr13 substrates are evaluated by cantilever beam method. The results show that the mean and local residual stresses in Cu films and Ag films decrease abruptly with the film thickness, then tend to be stable. The residual stress in the two kinds of films mainly originates from the interfacial misfit strain. Their interfacial stress is very large and the growing stress is small. The mean value of residual stress in thin Cu films is very large, even beyond the fracture strength of the bulk Cu material.
Mean and local residual stresses in Cu films and Ag films on 4Cr13 substrates are evaluated by cantilever beam method. The results show that the mean and local residual stresses in Cu films and Ag films decrease abruptly with the film thickness, then tend to be stable. The residual stress in the two kinds of films mainly originates from the interfacial misfit strain. Their interfacial stress is very large and the growing stress is small. The mean value of residual stress in thin Cu films is very large, even beyond the fracture strength of the bulk Cu material.
