Ductile-to-brittle transition in a Ti-based bulk metallic glass

The effects of changes in cooling rate on the density, elastic constants and fracture energy have been determined for Ti40Zr25Cu12Ni3Be20 bulk metallic glass. It is shown that changes in cooling rate directly affect the measured density and elastic constants, while the fracture energy, ranging from 148.9 to only 0.2 kJ m−2, is also shown to correlate with these changes in cooling rate/density/elastic constants. The critical Poisson’s ratio for toughness in this alloy system is 0.35, somewhat higher than that obtained in other metallic glasses, although consistent with recent theoretical predictions. Further correlations with these changes in toughness on the fracture surface appearance are provided.