Effects of ECAP Process and Aging On Mechanical and Superelastic Behaviors of Ni-Free Ti Based Smas

Ni-free Ti based shape memory alloys are promising functional materials for medical applications. The mechanical properties and superelasticity of these metastable βphse Ti based SMAs are sensitive to aging and thermal-mechanical treatment. Effects of severe plastic deformation-ECAE and aging on superelastic behaviors of Ni-free Ti based shape memory alloys have been investigated. Superelatic behaviors observed for aged Ti-Mo based alloy are closely related with the morphology of αphase precipitates, as well as ω phase precipitates. Fine homogenously distributedαphase precipitates, as well as ω phase precipitates, result in the lost of superelasticity. Aging treatment at low temperature after ECAE process is in favor of superelasticity of Ti-Nb based alloy. The mechanisms of effect of severe plastic deformation and aging are discussed.