Formation and dilatation of shear bands in a Cu-Zr metallic glass: A free volume perspective

CG Tang and HL Peng and Y Chen and M Ferry, JOURNAL OF APPLIED PHYSICS, 120, 235101 (2016).

DOI: 10.1063/1.4972189

We report the tensile deformation behaviour of metallic glass Cu50Zr50 as a function of quenching rate using molecular dynamics simulations. The atomic-scale shearing is found to be independent of atomic free volume, and the macroscopic correlation between the yield strength and density (or average free volume) is a coincidence, whereby samples with large free volume also have a low density of shear-resistant local five- fold symmetry. In the relatively slowly quenched (<= 10(10) K/s) samples, shear bands have a dilatation about 0.5%, which compares well with recent experimental results. In contrast, although more active local shearing occurs in the rapidly quenched samples, shear banding is not observed. This is because the strain energy disperses into local atomic shearing at the macroscopically elastic stage and, hence, is not sufficient for shear band activation, resulting in homogeneous deformation and appreciable plasticity. Published by AIP Publishing.

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