Correlation between onset of yielding and free volume in metallic glasses

Based on the free volume model, a critical value of reduced free volume is proposed to be the sufficient condition for the onset of yielding in metallic glasses. The corresponding stress for the onset of yielding is found to be less than the macroscopically measured yield strength, which is consistent with experimental observations. The difference in deformability between brittle and plastic metallic glasses can be explained in terms of the free volume evolution in the localized shear zone.