Numerical study of lhe microstructure in ferromagnetic shape memory alloys

Abstract

The microstructural behavior of ferromagnetic shape memory alloys (FSMAs) is studied by means of simulations of a magnetoelastic model. The elastic part consists of a Ginzburg- Landau free energy, extended to include both long-range anisotropic interactions and disorder, whereas the magnetism is based on the micromagnetic theory. The model is able to reproduce several experimental microstructures. First, the pure elastic model is tested and the structural martensitic transformation, the shape memory e ect (SME) and the superelastic e ect are found. Simulations of the full magnetoelastic model show, at temperatures T < Tc, magnetic stripes within martensitic twins. The martensitic transformation and the evolution of the magnetization with T is observed by di erent values of applied magnetic eld. Also, the magnetic shape memory e ect is obtained and the evolution of microstructure is presented in the magnetic eld-temperature-strain curve. The parameters used in these simulations are experimental values corresponding to Fe-Pd FSMA.