Martensitic phase transformations in shape memory alloy: phase field modeling with surface tension effect

The coupled phase-field and elasticity equations are presented for multivariant martensitic phase transformations (PTs) to investigate the effect of surface tension on PTs. The finite element method is utilized to solve the coupled phase-field and elasticity equations for two dimensional problems. Several numerical examples for cubic-to-tetragonal PTs in NiAl shape memory alloy are studied including surface-induced pretransformation and transformation, the stress-and temperature-induced growth of a martensitic nucleus inside austenite, and temperature-and surface-induced martensitic PTs for single and two martensitic variants. The phase and stress fields are obtained and the crucial effect of surface tension on stress and nucleation and propagation of martensitic nanostructures is revealed and discussed. It is found that the surface tension can suppress nucleation so that a larger driving force is needed for PTs to happen. Also, it can significantly change the stress and phase field solution. Moreover, it can suppress the propagation of transformed region. (C) 2016 Published by Elsevier B.V.