Rearrangement surfaces under magnetic field and/or stress in Ni-Mn-Ga

The main goal of this paper is to predict the magneto-mechanical behaviour of the rearrangement process. In order to do it, a representation in magnetic domains of a Ni-Mn-Ga single crystal is done and macroscopic strain and magnetisation are deduced. Thermodynamics of irreversible processes and a micro-macro approach were used to establish the expression of the free energy of this single crystal. The driving force acting on the twin boundaries is written for an applied stress and/or an applied magnetic field. Surfaces of starting rearrangement are deduced for the most common 5 M twinned martensite. Magnetocrystalline anisotropy is taken into account and shows its limitation.