Correlation between the elastic modulus and the intrinsic plastic behavior of metallic glasses: The roles of atomic configuration and alloy composition

Recent reports suggest that Poisson's ratio (ν), or the related ratio of shear modulus G to bulk modulus B, indicates the potential of metallic glasses (MGs) to sustain plastic strain. Using molecular dynamics simulations of the Cu₆₄Zr₃₆ MG as a representative, we demonstrate why and how these elastic and plastic properties are correlated, in terms of the common structural origin underlying these mechanical behaviors in MGs. The full icosahedral ordering has been identified as the key structural feature in the Cu-Zr MGs that controls not only the G and the G/B (or ν), but also the initiation of shear localization and the intrinsic plasticity. Additional analysis of the Cu-Zr MGs of different compositions and MGs in different alloy systems reveals a general correlation of the plasticity with the G/B ratio, as the latter is able to represent and couple the effects of both the atomic configuration and the alloy composition.