Investigating the effect of nanovoid inelastic surface stress and the austenite–martensite interface inelastic stress on the martensitic growth at the nanovoid surface

Abstract

In this paper, the effect of nanovoid inelastic surface stress and austenite (A)–martensite (M) interface inelastic stress on the martensitic growth at the nanovoid surface is investigated. Within the phase field approach (PFA), the coupled Cahn–Hilliard and elasticity equations involving the nanovoid inelastic surface stress are solved to generate a nanovoid. Then, the coupled Ginzburg–Landau and elasticity equations involving both the A-M interface and nanovoid inelastic surface stresses are solved to capture the evolution of martensite in the presence of the nanovoid. A nanovoid concentration-dependent phase transformation (PT) kinetic coefficient is introduced which, in contrast to previous works, removes the unphysical transformation inside the nanovoid. The FEM implemented in the commercial software COMSOL is used to solve the system of equations. It is found that the nanovoid changes the PT morphology and decreases the transformation rate. Both the A-M interface and nanovoid inelastic surface stresses decrease the transformation rate which amount depends on initial and boundary conditions. The effect of the A-M inelastic interface stress on the total stress is more pronounced in the presence of nanovoid. Nevertheless, the nanovoid inelastic surface stress shows no significant effect on the PT critical stress. Moreover, the study of the PT critical temperature versus the gradient energy coefficient also revealed that both the A-M interface and nanovoid inelastic surface stresses have no significant effect on the PT critical temperature.