Rejuvenation and plasticization of Zr-based bulk metallic glass with various Ta content upon deep cryogenic cycling

Abstract

In this paper, the rejuvenation of Zr-Cu-Al-Ni-Ta bulk metallic glasses (BMGs) upon deep cryogenic cycling treatment (DCT) has been studied. The samples show rejuvenation upon DCT with an increased enthalpy of relaxation (ΔHrelax) and a decreased density. With more Ta addition, the BMGs can be rejuvenated to a higher energy state, that is, the increment in both ΔHrelax and reduced free volume is larger for the BMGs with a higher Ta content. The fracture strength and plastic strain under compression increase with Ta content due to the evolution of intrinsic heterogeneous microstructures. Furthermore, the DCT treated samples show even better plasticity than the as-cast counterparts for the more induced free volume, which contribute to the generation of multiple shear bands. This study proves the universality of DCT on rejuvenating Zr-based BMGs and explains the effect of composition on rejuvenation and plasticization behavior.