Enhancement of room-temperature plasticity in a bulk metallic glass by finely dispersed porosity

Abstract

Melts of Pd42.5Cu30Ni7.5P20 (at. %) held under pressurized hydrogen are cast into bulk metallic glass (BMG) rods with fine (20–30μm diameter) pores uniformly dispersed. The low overall porosities (<4%) lead to only small reductions in Young modulus and yield strength, but to dramatically enhanced plasticity in compression: Rupture energy as high as 295MJm−3, compared to 16MJm−3 for the pore-free BMG. The pores force the proliferation of shear bands below the overall failure stress, a process of interest for toughening BMGs, materials for which shear localization in deformation restricts structural applications.