The Gibbs–Thomson effect in magnetron-sputtered austenitic stainless steel films

Abstract

Magnetron sputtering of austenitic stainless steel AISI 316, which has a face-centred cubic structure (γ), leads to films exhibiting a body-centred cubic (α) structure or a mixture of α- and γ-phases. The microstructure of the deposited films was studied by Mössbauer spectroscopy, x-ray diffraction and transmission electron microscopy. With increasing deposition temperature a phase transformation from α- to γ-phase was observed in these films. Instantaneous recording of the electromotive force shows that nickel content and deposition temperature are crucial factors for phase stability and phase formation. In room temperature deposited stainless steel films, the phase transformation after vacuum annealing can be described by the Johnson–Mehl–Avrami kinetic model. These phase transformations in stainless steel films during annealing can be explained with the Gibbs–Thomson effect, where the grain boundary energy raises the Gibbs free energy.