Phase-field simulation of magnetic field induced microstructure evolution in γmn-based alloys

Abstract

γMn-based alloys mainly possess an antiferromagnetic martensitic structure at room temperature, in which the type of crystal structure changes with the magnetic structure. Therefore, it is commonly believed that the cubic-tetragonal structural transformation is caused by the magnetic transition. Due to small transformation distortion and high magnetic field being required to present strong magnetism, the microstructure evolution of γMn-based alloys under an external magnetic field has rarely been experimentally revealed. In this paper, a phase-field model based on the related antiferromagnetic energies is proposed to investigate the microstructure evolution during magnetization. The simulated results show that the microstructure after martensitic transformation exhibits a self-accommodated twinning pattern. Upon magnetic loading, two transition stages, i.e., the reorientation stage of antiferromagnetic domains and the antiferromagnetic-ferromagnetic transition stage, would successively appear. External stress directly affects the relative stability among martensitic variants, thereby indirectly influencing the magnetization behavior, and the effect is related to the stress direction. Although the microstructure changes with the external condition, the interfacial migration of martensitic variant domain (or the martensitic twin boundary) and magnetic domain could keep in accordance with each other due to the strong magnetoelastic coupling.