A concurrent high strength and ductility of 3D gyroidal nanoporous metallic glasses

Abstract

By using molecular dynamics simulations, we investigate the tensile response of nanoporous (NP) Cu50Zr50 metallic glasses (MGs) with 3D gyroidal structure. Similar to nanoporous crystalline metals, NP–MGs fail by the plastic necking of ligaments, but shear bandings (SBs) prevail in those thick–ligament specimens. Particularly, with ligament diameter decreasing to 2.34 nm, SBs are hardly observed due to the limit of translation from shear transformation zones, resulting in superior strength and ductility of NP–MGs. The critical ligament size to suppress the formation of SBs is much smaller than those calculated value in MGs. The observations reveal a design strategy that a concurrent high strength and ductility of MGs could be obtained by designing 3D nanoporous structure with supra–nano size. The scaling laws for Young's modulus and strength as functions of relative density and ligament diameters are addressed, consistent with those in nanoporous crystalline materials.