Study on the strain partitioning behavior in heterostructured complex-concentrated alloy via high-resolution digital image correlation

Abstract

Here, we investigate the tensile deformation behavior in a Ni42Fe30Cr12Mn8Al5Ti3 complex-concentrated alloy with heterogeneously-grained structure consisting of fine and ultrafine grains containing nano-sized L12 precipitates. It is found that Lüders band initiation and propagation account for the early stage of deformation. High-resolution digital image correlation investigation reveals that there is strong strain partitioning between fine and ultrafine-grained domains upon plastic deformation. Significant strain gradient across the domain-interfaces is thus established. Strain partitioning promoted dense microshear bands are observed in the deformed alloy. They are uniformly distributed and interacted with each other, resulting in the formation of strain concentration zones, which are mostly evolved in fine-grained domains and some of them extend into ultrafine-grained domains at high strain levels. Thus, the global plastic deformation of the alloy is synergistically accommodated. Finally, local high stress in strain concentration zones in ultrafine-grained domains promotes the formation of voids at triple junctions of grain boundaries.