Rate-dependent plastic deformation of TiZrHfCuNiBe high entropy bulk metallic glass

Abstract

Rate-dependent plastic deformation behavior of TiZrHfCuNiBe high entropy bulk metallic glass (HE-BMG) is investigated by the nanoindentation and quasi-static compression tests. The experimental results reveal that the pop-in sizes during nanoindentation and the serrations sizes under compression will reduce when the loading/strain increases. The strain rate sensitivity during nanoindentation creep is enhanced as loading rate increases, which represents more homogeneously deformation of TiZrHfCuNiBe HE-BMG at higher loading/strain rate. The average serrations sizes of TiZrHfCuNiBe HE-BMG are significantly smaller than that of traditional bulk metallic glasses. The plastic deformation behavior of the TiZrHfCuNiBe HE-BMG is discussed with respect to the self-organized critical (SOC) state behavior. The results demonstrated that the shear-band interactions of multiple shear bands could affect the SOC behavior and inhomogeneous deformation. Research suggests the shear transformation zone (STZ) sizes become smaller as the loading rate increases based on the statistical analysis. It is ascribed to have a larger shear band density at lower loading/strain rate. The current research is in coincidence with the shear-band patterns shown in microscopic micrographs of specimen surfaces. More shear-banding distributions at the lower loading/strain rate will result in more inhomogeneous deformation.