Intrinsic shear strength of metallic glass

The intrinsic (ideal) strength has been extensively studied for crystalline alloys, but remains largely unsettled for metallic glasses. This study, by combining computer simulations and the cooperative shear model (Johnson and Samwer, 2005 [12]), found that, at the athermal limit, the yield strain of metallic glass can be as high as ∼10% in pure shear, and the corresponding ideal shear strength is G/10 (where G is the shear modulus), at which shear bands nucleate homogeneously in the metallic glass. The athermal extrapolation of the measured strength in conventional loading tests is much lower, owing to the unavoidable imperfections in realistic samples, where shear band nucleation is always heterogeneous and facilitated by stress concentrators. The two scenarios have different temperature dependence and merge at elevated temperatures, when the mode of yielding eventually changes from strain localization to homogeneous flow.