Our time is highly characterized by the use of increasingly widespread electromagnetic actuators, from larger to smaller scales. The development of efficient micro-actuators through the development of new materials is relevant, using for example the pseudo-elasticity of Shape Memory Alloys (SMA). The SMAs belong to the family of materials whose behavior is characterized by an austenite- martensite phase transformation. This transformation can be activated by heating or cooling and/or mechanical stress. Among the SMAs, Magnetic Shape Memory Alloys (MSMAs) are furthermore ferromagnetic. Under the action of a magnetic field, through the existence of a magnetostatic coupling as well as a magneto-mechanical coupling a phase transformation and/or a reorientation of martensite variants can occur. The behavior of these alloys is dependent of the amount of stress, temperature and/or magnetic field applied. Modeling the behavior of these complex alloys remains difficult but essential in order to determine and predict their response under complex loadings (multiaxial, heterogeneous) and extend their application range.

In this work, a coupled micromagnetic / phase field finite element modeling of MSMAs in a multiphysics framework with strong couplings (chemo-thermo-magneto-mechanical) is proposed in order to take the evolving nature of the microstructure into account. One of the main difficulties for the implementation of this model is the consideration of the exchange effects (defining both the domain walls and phase interfaces thickness), which are highly size and therefore mesh dependent.