Towards more uniform deformation in metallic glasses: The role of Poisson's ratio

We develop a quantitative analysis of how the plastic deformation in a metallic glass is more uniform if its Poisson ratio ν is higher. The plasticity of metallic glasses under ambient conditions is mediated by shear localized in thin bands, and can be characterized by experiments on the bending of thin plates. We extend the analysis by Conner et al. (Conner et al., J. Appl. Phys. 94 (2003), 904-911) of bands in bent plates to include the micromechanics of individual shear bands. Expressions are derived for the shear-band spacing and the offset on each band. Both these quantities are predicted to decrease as ν is increased. The predictions are tested against measurements on metallic glasses with a wide range of ν. Good agreement is found, supporting the new model for the shear-band spacing, and pointing the way towards more diffuse deformation, and consequently improved plasticity and toughness, of metallic glasses as ν increases toward the limiting value of 0.5.