An integrated model to predict the microstructure evolution and the mechanical behaviour of a two-phases pseudo-elastic SMA

Shape memory alloys (SMAs) are more and more used in many fields of mechanics and medicine. The reason for the success is the ability to recover the initial shape also after high values of deformation. During the deformation, the SMAs are able to change the structure from an initial one, often named as austenite, to a final one, named martensite. This transformation takes place at low temperature, and no recrystallization occurs, but the bulk of grains is interested by a structure changing. For that, this phenomenon cannot be qualified as a traditional structure transformation, but it is much more correct to talk about the transition of phase. The austenite-martensite transition is reversible, allowing a perfect recovery of the shape shown in the austenite phase. In this work, a model able to describe the microstructure evolution related to the mechanical behaviour of a SMA has been proposed. Results of FEM simulations have been compared with experimental ones both in terms of microstructure modifications and mechanical behaviour.