Cryogenic thermal cycling effects on serration behavior in wide glass transition temperature Zr-based bulk metallic glasses

•Effects of CTC on serration behavior in wide tg Zr-based BMGs were investigated.•The number and magnitude of stress drops correlate with the plasticity of BMGs.•BMGs with lower tg undergo strain hardening during plastic deformation.•Fine serrations occur easily in Zr-based BMGs with high Zr content and lower tg. Serration behavior serves as a pivotal link connecting micro-deformation mechanism to the mechanical properties of metallic glasses. To elucidate the impact of cryogenic thermal cycling (CTC) and compositional modifications on metallic glasses’ serration behavior, a series of Zr-based metallic glasses, exhibiting a broad range of glass transition temperatures (Tg), were meticulously manufactured. The stress drop magnitude initially decreases before the peak-rejuvenation induced by CTC, then gradually increases, while the number of stress drops exhibits an initial increase and then a decrease. These trends correlate with optimized plasticity of the metallic glasses. Remarkably, metallic glasses with lower Tg predominantly undergo strain hardening during plastic deformation. They exhibit lower viscosity in shear band zones and stress drop compared to others, attributed to the temperature increase around shear band zones approaching Tg. This phenomenon promotes shear band activation in smaller flow units, leading to finer serrations compared to glasses with higher Tg.