Strain rate dependence of inelastic strain recovery in ultrafine-grained Al films with different textures

Abstract: We investigated the tensile load–unload response and inelastic strain recovery in freestanding ultrafine-grained aluminum films with highly dissimilar texture at strain rates ranging from ~ 10^–6/s to 10^–3/s. For (110) textured bicrystalline films, the flow stress was nearly insensitive to strain rate and inelastic strain recovery both during and after unloading was small, leading to fairly low stress–strain hysteresis. In contrast, there was a substantial increase in flow stress for non-textured films with increasing strain rate. Furthermore, there was significant inelastic strain recovery both during and after unloading, resulting in a large stress–strain hysteresis. Interestingly, while the proportion of inelastic strain recovered during and after unloading varied with strain rate, the total strain recovery remained nearly constant. These observations underscore the influence of crystallographic texture and strain rate on the deformation mechanisms as well as the macroscopic behavior of ultrafine-grained metal films. Graphic abstract: [Figure not available: see fulltext.]