Micromechanical approach of stress-induced phase transformation

Abstract

Stress-induced martensitic phase transformation is responsible of very important phenomena like superelasticity or two-way shape memory in shape memory alloys. These phenomena are at the origin of many innovative products in industrial fields like aerospace or biomedical applications. To reach the best design is a very difficult task for applications using shape memory alloys: due to the existence of a phase transformation, these materials can no longer be considered as homogeneous and macroscopic approaches failed to give an accurate description of their behavior. The recent trend using SMA thin film as microactuator in microdevice increase the need of reliable design tools. Moderns concepts developed in micromechanics and finite element analysis are well adapted to deal with these problems. Intra and intergranular stresses building from transformation strain incompatibilities in bulk materials or thin films are well accounted using these tools, even when complex loading conditions or different initial crystallographic texture are considered.