Stress-induced martensitic transformation of a Ni54Fe19Ga27 single crystal in compression

This study investigated the pseudoelastic behavior of a Ni54Fe19Ga27 single crystal associated with stress-induced martensitic transformations in compression. The single crystal showed complete pseudoelasticity in four low-index crystallographic directions, including [100], [110], [111] and [112], but with clear anisotropy. The anisotropy includes transformation strains, apparent moduli of elasticity, critical stress for the transformation and selection of martensite variants. The critical stress was confirmed to obey Clausius-Clapeyron type relations on temperature, but with varying coefficients of dependence for different deformation directions. The value of (ⅆσf/ⅆT)εf was found to be nearly the same for the three deformation directions of [100], [110] and [111] but different for the [112] direction, implying a different stress-induced martensitic transformation in the [112] direction than that in the other three directions.