An empirical formula for composition demixing analysis in cathodic arc ion plating using alloy target is established based on the concepts of average charged state and relative demixing parameter. The level of composi...An empirical formula for composition demixing analysis in cathodic arc ion plating using alloy target is established based on the concepts of average charged state and relative demixing parameter. The level of composition demixing effect is presented by demixing degree of one element. For binary constituent alloy target, the composition change trend in coating is discussed and the limit of demixing degree for each element is determined. The content of one element with higher average charged state gets larger in coating than in alloy target, at meantime, the content of one element with lower average charged state gets less. For each one of the two constituents, the less the atom percent in alloy target, the larger the difference of its contents between the coating and the target. For triple constituent alloy target, the content change of one element with moderate average charged state is discussed in detail. Its content in coating getting larger or less is determined by the combination result of the contents of the other two elements in alloy target. For a given content of the element with moderate average charged state in triple alloy target, the content deviation level of that element from coating to alloy target will be not larger than that using binary alloy target containing only that element and one of the two others. According to the wanted coating composition, the composition design of alloy target is easily deduced from the formula.展开更多
The microstructure of the Al Ti alloy was studied.It was found that Al x Ti( x <5.0wt%) alloy consists of two phases,the solid solution of titanium in aluminum and the intermetallic compound Al 3Ti.The allo...The microstructure of the Al Ti alloy was studied.It was found that Al x Ti( x <5.0wt%) alloy consists of two phases,the solid solution of titanium in aluminum and the intermetallic compound Al 3Ti.The alloy was deformed by rolling and heat treated.The results show that the second phase precipitates are broken and refined in the matrix by large amount of cold work and crystalline grains are refined by annealing after the cold work.Deformation and heat treatment can improve the distribution of second phase of precipitates in the matrix to certain extent.展开更多
The studies were made on the preparation processes of the rare earth metal and alloy target materials and their characterization. In this work the rare earth metals were prepared by electrolysis of the oxide in molten...The studies were made on the preparation processes of the rare earth metal and alloy target materials and their characterization. In this work the rare earth metals were prepared by electrolysis of the oxide in molten salt for Nd metal and metallothermic reduction of the fluorides for Gd, Tb, Dy metals. After vacuum refining and distillation purification these rare earth metals were used for manufacturing the element targets, mosaic targets and as the starting materials of preparing the rare earth-transition metal (RE-TM) alloy targets. The four kinds of Dy-FeCo, NdDy-FeCo, Tb-FeCo and GdTb-FeCo alloy targets with diameter of 100 mm and thickness of 3 mm were prepared using powder metallurgical technique. The oxygen content and microstructure of the prepared RE-TM cast alloys and sintered targets were analyzed. The features and requirements of the RE-TM alloy sputtering target materials were also discussed.展开更多
High strength-to-weight ratio of non-ferrous alloys, such as aluminium, magnesium and titanium alloys, are considered to be possible replacement of widely accepted steels in transportation and automobile sectors. Amon...High strength-to-weight ratio of non-ferrous alloys, such as aluminium, magnesium and titanium alloys, are considered to be possible replacement of widely accepted steels in transportation and automobile sectors. Among these alloys, magnesium is self explosive and titanium is costlier, and aluminium is most likely to replace steels. Application of aluminium or its alloys is also thought of as an appropriate replacement in defence field, especially to enhance the easiness in mobility of combat vehicles while maintaining the same standard as that of conventional armour grade steels. Hence most of the investigations have been confined to aluminium or its alloys as base material and open an era of developing the newer composite materials to address the major limitation, i.e. tribological properties. The surface composites can be fabricated by incorporating the ceramic carbides like silicon carbide, carbides of transition metals and oxides of aluminium using surface modification techniques, such as high energy laser melt treatment, high energy electron beam irradiation and thermal spray process which are based on fusion route. These techniques yield the fusion related problems, such as interfacial reaction, pin holes, shrinkage cavities or voids and other casting related defects, and pave the way to need of an efficient technique which must be based on solid state. Recently developed friction stir processing technique was used in the present investigation for surface modification of AA7075 aluminum alloy, which is an alternative to steels. In the present investigation, 160 μm sized boron carbide powder was procured and was reduced to 60 μm and 30 μm using high energy ball mill. Subsequently these powders were used to fabricate the surface composites using friction stir processing.Ballistic performance testing as per the military standard(JIS.0108.01) was carried out. In the present work, an analytical method of predicting the ballistic behavior of surface composites was developed. This method was based on energy balance, i.e., the initial energy of impact is same as that of energy absorbed by multi layers. An attempt also has been made to validate the analytical results with the experimental findings. Variation between the analytical and experimental results may be accounted due to the assumptions considering such as isotropic behavior of target and shearing area of contact as cylindrical instead of conical interface As the analytical model yields the ballistic performance in the closer proximity of experimentally obtained, it can be considered to be an approximation to evaluate the ballistic performance of targets.展开更多
In order to understand the mechanism of conoidal fracture damage caused by a high-speed fragmentsimulating projectile in titanium alloy layer of a composite armor plate composed of titanium-and aluminum-alloy layers,t...In order to understand the mechanism of conoidal fracture damage caused by a high-speed fragmentsimulating projectile in titanium alloy layer of a composite armor plate composed of titanium-and aluminum-alloy layers,the ballistic interaction process was successfully simulated based on the Tuler eButcher and GISSMO coupling failure model.The simulated conoidal fracture morphology was in good agreement with the three-dimensional industrial-computed-tomography image.Further,three main damage zones(zones I,II,and III)were identified besides the crater area,which are located respectively near the crater area,at the back of the target plate,and directly below the crater area.Under the high-speed-impact conditions,in zone II,cracks began to form at the end of the period of crack formation in zone I,but crack formation in zone III started before the end of crack formation in zone II.Further,the damage mechanism differed for different stress states.The microcracks in zone I were formed both by void connection and shear deformation.In the formation of zone I,the stress triaxiality ranged from2.0 to1.0,and the shear failure mechanism played a dominant role.The microcracks in zone II showed the combined features of shear deformation and void connection,and during the formation process,the stress triaxiality was between 0 and 0.5 with a mixed failure mode.Further,the microcracks in zone III showed obvious characteristics of void connection caused by local melting.During the zone III formation,the triaxiality was 1.0e1.9,and the ductile fracture mechanism was dominant,which also reflects the phenomenon of spallation.展开更多
The effect of small variations of target hardness on the depth of penetration for nominally identical target material has not been addressed systematically in publications yet and is often neglected. An investigation ...The effect of small variations of target hardness on the depth of penetration for nominally identical target material has not been addressed systematically in publications yet and is often neglected. An investigation of this issue for laboratory-scale long rod projectiles penetrating into semi-infinite rolled-homogeneous-armor steel targets was conducted. The tungsten-heavy-alloy penetrators were of length 90 mm and diameter6 mm. Five lots of armor steel with a nominal hardness range of 280–330 BHN provided material for the targets. The pursued approach consisted of hardness testing of the targets, in total 17 ballistic experiments at velocities in between 1250 m/s and 1780 m/s and data analysis.A linear regression analysis of penetration vs. hardness shows that a target hardness increase within the given range of 280–330 BHN may result in a reduction of penetration depth of about 5.8 mm at constant velocity. This is equal to a change of-12% at an impact velocity of 1250 m/s. A multiple linear regression analysis included also the influence of yaw angle and impact velocity. It shows that small yaw angles and slight variations of impact velocities provide a smaller variation of the semi-infinite penetration depths than a variation of target hardness within a typical specification span of 50 BHN. For such a span a change in penetration of approximately-4.8 mm due to hardness variation is found, whereas 1°of yaw angle or-10 m/s of velocity variation gives a change of about-1.0 mm respectively-0.9 mm. For the given example, the overwhelming part of the variation is to be attributed to hardness effects – 4.8 mm out of 5.8 mm(83%). For nominally identical target material the target hardness thus influences the ballistic test results more severely than the typical scatter in impact conditions.展开更多
The atomic structures of liquid Ag-based binary alloys have been investigated in the solidification process by means of X-ray diffraction. The results of liquid structure show that there is a break point in the mean n...The atomic structures of liquid Ag-based binary alloys have been investigated in the solidification process by means of X-ray diffraction. The results of liquid structure show that there is a break point in the mean nearest neighbor distance r1 and the coordination number Nmin for glass-forming liquid, while the correlation radius rc and the coordination number Nmin display a monotone variational trend above the break point. It means glass-forming liquids have a steady changing in structure above liquidus and more inhomogeneous state at liquidus. We conclude that there is a strong correlation between liquid structure and glass forming ability in Ag-based binary alloys.展开更多
文摘An empirical formula for composition demixing analysis in cathodic arc ion plating using alloy target is established based on the concepts of average charged state and relative demixing parameter. The level of composition demixing effect is presented by demixing degree of one element. For binary constituent alloy target, the composition change trend in coating is discussed and the limit of demixing degree for each element is determined. The content of one element with higher average charged state gets larger in coating than in alloy target, at meantime, the content of one element with lower average charged state gets less. For each one of the two constituents, the less the atom percent in alloy target, the larger the difference of its contents between the coating and the target. For triple constituent alloy target, the content change of one element with moderate average charged state is discussed in detail. Its content in coating getting larger or less is determined by the combination result of the contents of the other two elements in alloy target. For a given content of the element with moderate average charged state in triple alloy target, the content deviation level of that element from coating to alloy target will be not larger than that using binary alloy target containing only that element and one of the two others. According to the wanted coating composition, the composition design of alloy target is easily deduced from the formula.
文摘The microstructure of the Al Ti alloy was studied.It was found that Al x Ti( x <5.0wt%) alloy consists of two phases,the solid solution of titanium in aluminum and the intermetallic compound Al 3Ti.The alloy was deformed by rolling and heat treated.The results show that the second phase precipitates are broken and refined in the matrix by large amount of cold work and crystalline grains are refined by annealing after the cold work.Deformation and heat treatment can improve the distribution of second phase of precipitates in the matrix to certain extent.
基金Former the Ministry of Metallurgical Industry of China (BJ95-06-01)
文摘The studies were made on the preparation processes of the rare earth metal and alloy target materials and their characterization. In this work the rare earth metals were prepared by electrolysis of the oxide in molten salt for Nd metal and metallothermic reduction of the fluorides for Gd, Tb, Dy metals. After vacuum refining and distillation purification these rare earth metals were used for manufacturing the element targets, mosaic targets and as the starting materials of preparing the rare earth-transition metal (RE-TM) alloy targets. The four kinds of Dy-FeCo, NdDy-FeCo, Tb-FeCo and GdTb-FeCo alloy targets with diameter of 100 mm and thickness of 3 mm were prepared using powder metallurgical technique. The oxygen content and microstructure of the prepared RE-TM cast alloys and sintered targets were analyzed. The features and requirements of the RE-TM alloy sputtering target materials were also discussed.
基金Financial assistance from Armament research board,New Delhi,India
文摘High strength-to-weight ratio of non-ferrous alloys, such as aluminium, magnesium and titanium alloys, are considered to be possible replacement of widely accepted steels in transportation and automobile sectors. Among these alloys, magnesium is self explosive and titanium is costlier, and aluminium is most likely to replace steels. Application of aluminium or its alloys is also thought of as an appropriate replacement in defence field, especially to enhance the easiness in mobility of combat vehicles while maintaining the same standard as that of conventional armour grade steels. Hence most of the investigations have been confined to aluminium or its alloys as base material and open an era of developing the newer composite materials to address the major limitation, i.e. tribological properties. The surface composites can be fabricated by incorporating the ceramic carbides like silicon carbide, carbides of transition metals and oxides of aluminium using surface modification techniques, such as high energy laser melt treatment, high energy electron beam irradiation and thermal spray process which are based on fusion route. These techniques yield the fusion related problems, such as interfacial reaction, pin holes, shrinkage cavities or voids and other casting related defects, and pave the way to need of an efficient technique which must be based on solid state. Recently developed friction stir processing technique was used in the present investigation for surface modification of AA7075 aluminum alloy, which is an alternative to steels. In the present investigation, 160 μm sized boron carbide powder was procured and was reduced to 60 μm and 30 μm using high energy ball mill. Subsequently these powders were used to fabricate the surface composites using friction stir processing.Ballistic performance testing as per the military standard(JIS.0108.01) was carried out. In the present work, an analytical method of predicting the ballistic behavior of surface composites was developed. This method was based on energy balance, i.e., the initial energy of impact is same as that of energy absorbed by multi layers. An attempt also has been made to validate the analytical results with the experimental findings. Variation between the analytical and experimental results may be accounted due to the assumptions considering such as isotropic behavior of target and shearing area of contact as cylindrical instead of conical interface As the analytical model yields the ballistic performance in the closer proximity of experimentally obtained, it can be considered to be an approximation to evaluate the ballistic performance of targets.
基金This work was supported by the National Natural Science Foundation of China(Grant No.51571031).
文摘In order to understand the mechanism of conoidal fracture damage caused by a high-speed fragmentsimulating projectile in titanium alloy layer of a composite armor plate composed of titanium-and aluminum-alloy layers,the ballistic interaction process was successfully simulated based on the Tuler eButcher and GISSMO coupling failure model.The simulated conoidal fracture morphology was in good agreement with the three-dimensional industrial-computed-tomography image.Further,three main damage zones(zones I,II,and III)were identified besides the crater area,which are located respectively near the crater area,at the back of the target plate,and directly below the crater area.Under the high-speed-impact conditions,in zone II,cracks began to form at the end of the period of crack formation in zone I,but crack formation in zone III started before the end of crack formation in zone II.Further,the damage mechanism differed for different stress states.The microcracks in zone I were formed both by void connection and shear deformation.In the formation of zone I,the stress triaxiality ranged from2.0 to1.0,and the shear failure mechanism played a dominant role.The microcracks in zone II showed the combined features of shear deformation and void connection,and during the formation process,the stress triaxiality was between 0 and 0.5 with a mixed failure mode.Further,the microcracks in zone III showed obvious characteristics of void connection caused by local melting.During the zone III formation,the triaxiality was 1.0e1.9,and the ductile fracture mechanism was dominant,which also reflects the phenomenon of spallation.
基金supported financially by the Bundesministerium der Verteidigung (BMVg)the Bundesamt für Ausrüstung, Informationstechnik und Nutzung der Bundeswehr (BAAINBw)
文摘The effect of small variations of target hardness on the depth of penetration for nominally identical target material has not been addressed systematically in publications yet and is often neglected. An investigation of this issue for laboratory-scale long rod projectiles penetrating into semi-infinite rolled-homogeneous-armor steel targets was conducted. The tungsten-heavy-alloy penetrators were of length 90 mm and diameter6 mm. Five lots of armor steel with a nominal hardness range of 280–330 BHN provided material for the targets. The pursued approach consisted of hardness testing of the targets, in total 17 ballistic experiments at velocities in between 1250 m/s and 1780 m/s and data analysis.A linear regression analysis of penetration vs. hardness shows that a target hardness increase within the given range of 280–330 BHN may result in a reduction of penetration depth of about 5.8 mm at constant velocity. This is equal to a change of-12% at an impact velocity of 1250 m/s. A multiple linear regression analysis included also the influence of yaw angle and impact velocity. It shows that small yaw angles and slight variations of impact velocities provide a smaller variation of the semi-infinite penetration depths than a variation of target hardness within a typical specification span of 50 BHN. For such a span a change in penetration of approximately-4.8 mm due to hardness variation is found, whereas 1°of yaw angle or-10 m/s of velocity variation gives a change of about-1.0 mm respectively-0.9 mm. For the given example, the overwhelming part of the variation is to be attributed to hardness effects – 4.8 mm out of 5.8 mm(83%). For nominally identical target material the target hardness thus influences the ballistic test results more severely than the typical scatter in impact conditions.
基金support by the National Basic Research Program of China (Grant No. 2007CB613901)the National Natural Science Foundation of China (Grant Nos. 50831003 and 50871062)
文摘The atomic structures of liquid Ag-based binary alloys have been investigated in the solidification process by means of X-ray diffraction. The results of liquid structure show that there is a break point in the mean nearest neighbor distance r1 and the coordination number Nmin for glass-forming liquid, while the correlation radius rc and the coordination number Nmin display a monotone variational trend above the break point. It means glass-forming liquids have a steady changing in structure above liquidus and more inhomogeneous state at liquidus. We conclude that there is a strong correlation between liquid structure and glass forming ability in Ag-based binary alloys.
