Macroscopic response of Ni-Mn-Ga single crystals considering the effects of residual reorientation strain and temperature

The magnetic field-induced and stress-induced response of magnetic shape memory alloy was investigated in the present study. Based on thermodynamic approach, a one-dimensional constitutive model was derived containing demagnetization energy and chemical energy. A cosine function was constructed to predict the variant volume fraction during reorientation process, considering the presence of residual reorientation strain. The effects of temperature on the magnetization behaviour, domain fraction and magnetization angle were discussed. Owing to the presence of residual reorientation strain, the critical threshold fields in hysteresis loop were decreased as a linear function of residual variant volume fraction. With increasing temperature, critical fields for domain and magnetic rotation to saturation were decreased, and critical threshold fields would increase for the stress-induced reorientation. The comparisons between numerical results and experimental results showed that the present model can effectively predict the macroscopic response of magnetic shape memory alloy, considering the effects of temperature and residual reorientation strain.