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本文研究了Ti-5Al-8Ni和Ti-5Al-8Co合金低温高应变速率下的超塑性性能和超塑性加工后组织形貌。表明:m值随温度与应变速率的变化是由两种不同机制所控制;Ti-5Al-8Ni合金在740℃以下超塑性加工后组织不均匀,超塑性对应变速率很敏感;Ti-5Al-8Co合金在740℃以下超塑性加工后组织均匀,且无明显长大,在725℃显示>700％的延伸率,超塑性对应变速率不敏感,在780℃超塑性,在断口附近组织中有索氏体存在,有可能得到好的室温塑性。
In this paper, the superplasticity and microstructure of Ti-5Al-8Ni and Ti-5Al-8Co alloys under low temperature and high strain rate were investigated. The results show that the change of m value with temperature and strain rate is controlled by two different mechanisms. The microstructure of Ti-5Al-8Ni alloy is not uniform after the superplastic process below 740 ℃, and the superplasticity is very sensitive to the strain rate. Ti-5Al- The microstructure of the 8Co alloy is uniform after 740 ℃ and superplasticity without obvious growth. It shows an elongation of> 700% at 725 ℃. The superplasticity is not sensitive to the strain rate and superplasticity at 780 ℃. In the vicinity of the fracture, Sorbite exists, it is possible to get good room temperature plasticity.