Phase-field modelling of magnetically induced microstructure evolution in martensitic polycrystals

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The magnetomechanical responses of magnetic shape memory (MSM) alloys to external magnetic fields are correlated with the coupled magneto-elastic domain structure evolutions in these materials. Hence, the kinetic pathways of the domain evolutions play a key role in determining the materials properties. Mesoscopic simulations based on phase-field modelling can provide valuable information to understand the dynamic processes and main quantities affecting the MSM effect. Therefore the aim of this project is to develop both, a new phase-field model and parallel 3D simulator for MSM alloys. The model formulation includes elastic, magnetic and elastomagnetic free energy contributions and different martensitic crystal structures. The thermodynamical data and free energies of the considered binary Fe-Pd and Fe-Pt and ternary Ni-Mn-Ga alloys needed to configurate the phase-field model will be exchanged from cooperating groups of the SPP 1239. The framework should be capable to describe the magnetic-field-induced evolution of polycystalline and polytwinned microstrüctures, of discontinuous structures with different twin boundaries and compositions, of the coupled process of grain growth (coarsening) and magnetically driven grain boundary motion, of grain- and twin-boundary diffusion and segregation patterns.