Composition dependence of mechanically-induced structural rejuvenation in Zr-Cu-Al-Ni metallic glasses

With the aim of studying the effect of composition on structural rejuvenation, high-pressure torsion was performed on Zr55Cu30Ni5Al10 and Zr65Cu18Ni7Al10 metallic glasses. Nanoindentation measurements showed that structural rejuvenation in these two alloys was accompanied by a transition in deformation mode from localized deformation to a more homogenous deformation. The rejuvenated samples also exhibited strain-softening and improved plasticity. The increase in relaxation enthalpy of Zr55Cu30Ni5Al10 metallic glasses was larger than that of Zr65Cu18Ni7Al10, indicating different extents of structural rejuvenation. The influence of composition on the extent of structural rejuvenation was assessed for different systems of metallic glasses in the literature from the perspective of atomic clusters and liquid fragility. It was concluded that metallic glasses formed from more fragile liquids could be more susceptible to mechanically-induced rejuvenation.