Topological changes and deformation mechanisms of nanoporous Ta under compression

Abstract

While the mechanical behavior of noble nanoporous metals has been the subject of numerous studies, less is known about their recently developed refractory-based counterparts. Here we report on the mechanical properties, deformation mechanisms and topological changes of nanoporous tantalum, a prototypical refractory metal, by means of atomistic simulations of compression tests. An open-source multi-cpu and gpu-capable software is presented and used for the generation of computational samples. The stress–strain curves show a non-linear elastic response, with early yielding. The plastic regime is first characterized by a linear hardening followed by an exponential hardening at large strains, associated with a high degree of densification. Plasticity is dominated by dislocation activity, with twinning and vacancy formation appearing as complementary deformation mechanisms. In order to study the mechanical response from a topological perspective, we track the evolution of the genus throughout the tests, finding direct correlations with each regime of the stress–strain curves. The results are in agreement with previous studies of plasticity in nanoporous metals and highlight the importance of using topological metrics, for gaining insights into complex aspects of the deformation of nanoporous metals.