LAUSR

Abstract The holding time effect on the mechanical property, creep behavior and shear transformation zone has been systematically investigated by performing a series of nanoindentation creep measurements on magnetron-sputtered La-Co-Al, Zr-Cu-Ni-Al, Ni-Nb and W-Ru-B thin film metallic glasses. When the variation of contact stiffness with indentation depth is considered, the hardness, Young's modulus and strain rate have been found to decrease with increasing holding time. Meanwhile, strain rate sensitivity ( m ), and the volume and activation energy of shear transformation zone (STZ) have been analyzed, according to the cooperative shear model, at different stages of creep to explain the time-dependent mechanical behavior and properties. The higher strain rate results in few potential STZs with larger volume and activation energy, and the lower plastic stability of deformation manifested by smaller m , at the primary creep stage, as compared with those at apparent steady-state creep. Therefore, easier STZ activation, at longer holding time and lower strain rate, conduces to profuse operation of STZs and larger critical size for deformation mode transition from highly-localized to non-localized.