Effect of Structural Relaxation on Deformation Behaviour of Zr-Based

Structural relaxation through isothermal annealing at temperature below glass transition is conducted on Zr_46.75Ti_8.25Cu_7.5Ni₁₀Be_27.5 (Vitreloy-4) bulk metallic glass. Defect concentration is correlated with the annealing time t according to differential scanning calorimetry thermalgrams. The effects of structural relaxation on mechanical properties and deformation behaviour are investigated by using instrumented nanoindentation. It is found that the as-cast alloy exhibits pronounced serration flow during the loading process of nanoindentation, and the size and number of the serrations decrease with the annealing time. The change of the deformation behaviour with structural relaxation is explained using a free volume model.