Hf-based bulk metallic glasses with critical diameter on centimeter scale

New Hf-based bulk metallic glasses (BMGs) have been discovered in the Hf–Cu–Ni–Al quaternary system. These interesting BMGs (i) are based on a refractory element and have relatively high glass transition and crystallization temperatures, (ii) exhibit excellent glass-forming ability with a critical diameter in the 8–10 mm range for copper mold casting, and (iii) have relatively high mass density (>∼11 g/cc). The combination of these properties is important for the BMG matrix in composites for kinetic energy penetrator applications.