Deformation behavior of Zr60.0Al15.0Ni25.0 metallic glass

The effect of thermal crystallization on viscous flow of supercooled liquid in Zr60Al15Ni25 metallic glass was investigated. Zr6Al2Ni crystalline precipitates with ellipsoidal morphology appeared during thermal annealing and deformation at high temperatures. No significant difference in phase selection or morphology of crystalline precipitates was observed between non-deformed and deformed specimens. The viscous flow behavior is very sensitive to the strain rate and the stress-strain behavior can be classified into three types depending on the strain rate: stress overshoot mode, stable viscous flow mode with constant flow stress, and strain hardening mode. The strain hardening is caused by the precipitation of Zr6Al2Ni phase from supercooled liquid. The flow stress increased with increase in the crystallization ratio for specimens containing a volume fraction of Zr6Al2Ni phase higher than 10% although the stress showed no significant change with slight crystallization.