Abstract
The martensitic transformation behavior under coupling temperature and high magnetic field in TiNi paramagnetic shape memory alloy was studied by using the modified Landau model. In order to introduce the effect of high magnetic field, the Fermi surface total density of state (DOS) of TiNi alloy under different phase-transformed shear strain (order parameter) was calculated by using the first-principles calculations, then the relationship between magnetic susceptibility and shear strain was carried out. The calculation results from the modified Landau model involving the effect of magnetic free energy indicated that the martensitic transformation temperatures (M(s) and T(0)) suddenly increase. It can be mainly contributed to the parabola increasing of martensitic transformation driving force under coupling temperature and high magnetic field. Also, it is found that the oriented growth of martensitic variants occurs under coupling temperature and high magnetic field due to the increased difference of free ener