Cyclic cryogenic pretreatments influencing the mechanical properties of a bulk glassy Zr-based alloy

In this study, cryogenic thermal cycling was applied to bulk glassy Zr52.5Cu17.9Al10Ni14.6Ti5 (Vitreloy 105) bending samples. After that, significantly improved plasticity and better fatigue properties at three-point bending as well as higher impact toughness were measured in dependence of the duration and the cooling rate of the thermal cycling process. This improved material behaviour is caused by reinforced shear banding, visible in scanning electron microscopy at the side faces of the specimens after fracture. A comprehensive analysis of the fracture surfaces of both quasi-static and cyclic bent specimens revealed intense crack propagation along major shear bands and increased fatigue fracture regions, respectively. It is supposed that there is a structural rejuvenation due to the local variations of the thermal expansion coefficients within the multicomponent alloy affecting the mechanical properties.