Atomistic investigation on the mechanical properties of 3D nanoporous metallic glasses under uniaxial tension and compression

Nanoporous metallic glasses (NPMGs) have a combination of superior properties of metallic glasses and porous structures. Comprehending the inherent deformation and failure mechanisms of NPMGs subjected to complex loading conditions is of great importance to transferring it from scientific research to realistic multifunctional applications, as well as optimize the bottom-up design of NPMGs working in extreme conditions. However, deficiencies in state-of-the-art positioning characterization methods and the microstructure complexity remain tremendous obstacles for the in-situ investigation of deformation processes completely based on real experiments. In this work, molecular dynamics simulations of tensile and compressive tests of 3D NPMGs with diamond and gyroid structures are presented to investigate the mechanical behaviors, as well as deformation processes at the atomic level. Our results suggest that the 3D NPMGs have excellent properties such as lightweight, high strength, and enhanced ductility, which is distinct from bulk metallic glasses lacking global-plasticity. The mechanical behaviors of NPMGs strongly depend on the relative density and ligament size. A tension-compression asymmetry is observed due to the non-negligible surface effects in NPMGs. The influence of surface stress on the mechanical properties becomes slighter with the increment of relative density. This work reveals an atomic-level understanding of the inherent deformation modes of NPMGs, promoting the multifunctional applications of metallic glasses-based materials.