Enhanced plastic strain in Zr-based bulk amorphous alloys

Abstract

Bulk metallic glasses subjected to quasistatic uniaxial compression at room temperature typically display large elastic strains but limited plastic flow of 0--2% before failure. We have developed an amorphous alloy, ${\mathrm{Zr}}_{59}{\mathrm{Ta}}_{5}{\mathrm{Cu}}_{18}{\mathrm{Ni}}_{8}{\mathrm{Al}}_{10},$ which experiences an average macroscopic plastic strain of 4.5% before failure. The as-cast alloy shows no evidence for the presence of crystalline phases, and displays a distinct glass transition temperature and a wide supercooled liquid region. Upon compression beyond the yield point, the alloy develops shear bands which show a pronounced tendency for branching. We propose that this shear band branching distributes the plastic strain on the shear band, thereby suppressing crack initiation and allowing the material to experience a large macroscopic plastic strain before failure.