Predicting The Effect Of Crystallography On The Performance Of High Temperature Shape Memory Alloys Subjected To Viscoplastic Deformations

High temperature Shape Memory Alloys (HTSMAs) are materials which can actuate at temperatures between 100 – 400 deg C by phase transformations and recover permanent strains (deformations) produced due to thermomechanical loads. In addition to these loads, localized stresses get generated which tend to be much higher than the macroscopic stresses. This phenomena results in pinning of the martensite phase inside the austenite phase by dislocations and cause degeneration in the material properties and characteristics such as creep resistance and shape memory effect. The present work examines this phenomena at the grain scale through a three-dimensional elasto-viscoplastic constitutive model accounting for the shape memory behavior of HTSMAs, the viscoplastic flow at high temperatures and the coupling between them, built on a crystal plasticity framework. An investigating of the effect of texture on the material performance is also carried out.