Ti－12Co－5Al合金的超塑变形

SUPERPLASTIC DEFORMATION OF Ti-12Co-5Al ALLOY

采用合适的冶炼及形变热处理工艺获得了具有超细化α－Ｔｉ／Ｔｉ２Ｃｏ双相组织的Ｔｉ－１２Ｃｏ－５Ａｌ合金板材，该合金呈现出优异的高速低温超塑性，在７００℃和３×１０－２ｓ－１的高应变速率条件下延伸率超过２０００％。微观组织研究表明超塑变形促进了Ｔｉ２Ｃｏ粒子的长大和形状变化，在塑性应变高达１５５０％时试样中仍无孔洞产生，应变硬化和应变速率硬化的共同作用是该合金具有优异超塑性的根本原因。

An Ti-12Co-SAl alloy sheet with an ultra fine α-Ti/Ti2Co microstructure was prepared by proper smelting and thermomechanical treatment. An excellent superplastic elongation more than 2000% was obtained at high strain rate of3 ×10-2 s-1 and under relatively low temperature of 700℃. Microstructural study indicates that the supepolastic defomration promotes the grain growth and shape change of the Ti2Co intermetallic particles.No cavity was found in the specimen after even superplastically deformed to 1550%. The combination of strain hardening, resulted from the coarsening of α-Ti grains and Ti2Co particles, together with the strain rate hardening is considered to be the main reason why the alloy exhibits excellent superplasticity.