Twinning in Ni–Fe–Ga–Co shape memory alloy: Temperature scaling beyond the Seeger model

Abstract

The temperature dependence of the macroscopic de-twining stress in Ni–Fe–Ga–Co shape memory alloy is proportional to the temperature dependence of the micro-yield stress. This proportionality holds for all values of the reversible anelastic strain derived from non-linear internal friction experiments and contradicts predictions of the Seeger model for the temperature dependence of the yield stress. The Seeger model requires two length scales which leads to the independence of two yield stress components. Instead, we find the self-affine behaviour of anelastic strain, which excludes all separations of lengthscales.