摘要
TiNi and Ti-based shape memory alloys were processed by equal channel angular pressing （ECAP） at 673-773 K along Bc route to obtain ultrafine grains for increasing the strength of parent phase and improving the functional properties. The effects of both thermodynamically stable and metastable second phases on the mechanical properties and martensitic transformations of these alloys were investigated. It is found that thermodynamically stable Ti2Ni phase has no effect on martensitic transformation and superelasticity of Ti-rich TiNi alloy, thermodynamically stable α phase is harmful for ductility of Ti-Mo-Nb-V-Al alloy, but metastable Ti3Ni4 phase is effective for R phase transformation, martensitic transformation and superelasticity of Ni-rich TiNi alloy. The mechanisms of the second phases on the martensitic transformations and mechanical properties were discussed.
借助ECAP技术对TiNi合金和Ti-Mo基记忆合金在673~773K进行挤压处理,挤压路径为Bc,以获得超细晶组织,从而增强母相的强度,改进材料的性能。研究热力学稳定相及亚稳相对这两种合金的力学性能和马氏体转变的影响。结果表明,对于富钛TiNi合金,热力学稳定相Ti2Ni对马氏体转变及超弹性没有影响,而稳定相α相则可造成Ti-Mo-Nb-V-Al塑性降低。亚稳Ti3Ni4相对富镍TiNi合金的R相变、马氏体转变及超弹性有很大影响。并对第二相对TiNi合金和Ti-Mo基合金力学性能、马氏体转变的影响进行分析。
基金
Project (50671067) supported by the National Natural Science Foundation of China
Project (09JC1407200) supported by the Science and Technology Committee of Shanghai, China
