Effect of structural relaxation on the deformation behavior of A Zr _64.13Cu_15.75Ni_10.12Al₁₀ bulk metallic glass under nanoindentation

Structural relaxation by isothermal annealing below the glass transition temperature is conducted on a Zr_64.13Cu_15.75Ni _10.12Al₁₀ bulk metallic glass. The effect of structural relaxation on thermal and mechanical properties was investigated by differential scanning calorimetry and instrumented nanoindentation. The recovery of the enthalpy in the DSC curves indicates that thermally unstable defects were annihilated through structural relaxation. During nanoindentation, the structural relaxation did not have a significant influence on the serrated plastic flow behavior. However, Structural relaxation shows an obvious effect in increasing both the hardness and elastic modulus, which is attributed to the annihilation of thermally unstable defects that resulted from the relaxation.