Preparation And High-Temperature Compression Deformation Of Ti-Al Composites

Ti-Al composites were fabricated by powder metallurgy using TiH₂ as raw material. The dehydrogenation of TiH₂, the fabrication technology of Ti-Al composites and the high-temperature compression of the composites were researched. In the process of the dehydrogenation of TiH₂, firstly characteristics of thermal decomposition of TiH₂ were researched by Differential Thermal Analysis (DTA).And then in a vacuum furnace (the vacuum of 10-2Pa),the dehydrogenation process of TiH₂ was systematically studied. The effect of heating temperature and holding time on the dehydrogenation of TiH₂ were researched, which is in order to determine the optimal parameters of the dehydrogenation of TiH₂. In the process of the fabrication of Ti-Al composites,The effect of heating temperature and holding time on microstructure were investigated. The high-temperature compression tests of Ti-Al composites were tested on the electronic universal testing machine, the effect of temperature and strain rate on plastic deformation ability of the materials were studied.The characteristics of thermal decomposition of the mixed powders of TiH₂ and Al were researched by Differential Thermal Analysis (DTA). The results show that: the decomposition temperature was range from 470℃to 690℃and the endothermic peaks were found at 550℃.Under vacuum, when the mixed powders of TiH₂ and Al were dehydrogened at the temperature of 610℃, the best holding time is 90min.The mixed powders which were dehydrogened at the temperature of 520℃for 30min and 550℃for 90min contained Ti, Al, and a small amount of TiAl3, that was TiH₂ completely decomposed.The process of the fabrication of Ti-Al composites was studied, which mainly included one-step sintering and two-step sintering. The results show that: Ti-Al composites were successfully fabricated by two-step sintering,The Ti-Al composites sintered at 580℃for 90min and 650℃for 40min contained Ti, Al and a small amount of TiAl3, but sintered at 580℃for 90min and 670℃for 20min the Ti-Al composites contained Ti,a small amount of Al and a lot of TiAl3.The ductility of Ti-Al composites was assessed by high-temperature compression tests. The results show that at the strain rate of 1.67×10-3 s-1, The Ti-Al composites which sintered at 580℃for 90min and 650℃for 40min and compressed at 600℃possessed the best ductility, whose peak stress was 254MPa.However the Ti-Al composites which sintered at 580℃for 90min and 670℃for 20min and compressed at 700℃possessed the best ductility, whose peak stress was 266MPa, But with the strain rate increased, the ductility were continuously decreasing.