The Influence of Viscous Flow Deformation on the Thermal Stability and Hardness of ZrCuAlNi Bulk Glassy Alloy

Abstract

We investigated the thermal stability and hardness of a Zr55Cu30Al10Ni5 bulk glassy alloy after isothermal viscous flow deformation in the supercooled liquid region. The influence of deformation temperature, holding time and initial strain rate on the thermal stability and hardness of aZ r 55Cu30Al10Ni5 bulk glassy alloy subjected to the high temperature compression test was examined by differential scanning calorimetry (DSC) and with a Vickers micro-hardness tester. The results showed that the incubation time for isothermal annealing crystallization reduced during the viscous flow deformation. Thermal stability of supercooled liquid decreased after viscous flow deformation. As the deformation temperature increased, the SCL region decreases. At lower temperatures below 713 K the structural relaxation occurred, resulting in a slight increase in hardness. The crystallization at higher temperatures of over 723 K caused a rapid increase in hardness. The supercooled liquid region decreased and the hardness increased with increasing deformation time. Higher strain rate resulted in larger deformation in the same deformation time, and had slight influence on the thermal stability and hardness of the Zr55Cu30Al10Ni5 glassy alloy. When the Zr55Cu30Al10Ni5 bulk glassy alloy was compressed for 300 s with an initial strain rate of 3:3 � 10 � 3 s � 1 at the temperatures of 723 K, nanocrystallization occurred, and the grain size was evaluated to be smaller than 5 nm. [doi:10.2320/matertrans.MJ200712]