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

摘要

Melts of Pd_(42.5)Cu_(30)Ni_(7.5)P_(20) (at. %) held under pressurized hydrogen are cast into bulk metallic glass (BMG) rods with fine (20-30 μm 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 295 MJ m~(-3), compared to 16 MJ m~(-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.