Multiscale nanoindentation modelling of concentrated solid solutions: A continuum plasticity model

Recently developed single-phase concentrated solid-solution alloys (CSAs) contain multiple elemental species in high concentrations with different elements randomly arranged on a crystalline lattice. These chemically disordered materials present excellent physical properties, including high-temperature thermal stability and hardness, with promising applications to industries at extreme operating environments. The aim of this paper is to present a continuum plasticity model accounting for the first time for the behaviour of a equiatomic five-element CSA, that forms a face-centred cubic lattice. The inherent disorder associated with the lattice distortions caused by an almost equiatomic distribution of atoms, is captured by a single parameter alpha that quantifies the relative importance of an isotropic plastic contribution to the model. This results in multiple plasticity mechanisms that go beyond crystallographic symmetry-based ones, common in the case of conventional single element metals. We perform molecular dynamics simulations of equiatomic CSAs: NiFe, NiFeCr, NiFeCrCo, and Cantor alloys to validate the proposed continuum model which is implemented in the finite element method and applied to model nanoindentation tests for three different crystallographic orientations. We obtain the representative volume element model by tracking the combined model yield surface.

Automated summary

Recently developed CSAs are chemically disordered materials with high concentrations of multiple elemental species randomly arranged on a crystalline lattice. They possess excellent physical properties, making them attractive for industries operating in extreme environments. This paper presents a continuum plasticity model for equiatomic five-element CSAs, which captures the inherent disorder associated with lattice distortions through a single parameter alpha. Molecular dynamics simulations of different CSAs are performed to validate the proposed model, which is then applied to nanoindentation tests for various crystallographic orientations using the finite element method.