Pure shear deformation and its induced mechanical responses in metallic glasses.

Shear is a basic deformation mode governing yielding, plasticity and fracture in metallic solids. For amorphous metals, due to various constraints, little work is available in addressing directly shear deformation and shear-induced mechanical property changes which are vital to the mechanistic understanding of this new class of disordered materials. Here, by using a finite deformation theory, we examine the pure shear deformation in a bulk metallic glass in a large range of shear strains. With the continuum approach, we show systematically for the first time the detailed shear deformation behaviours, shear-induced normal stress and strain relations, softening in the elastic constants, volume dilatation and free energy change induced by the shear deformation. These results point to two major consequences from the shear deformation, one is the mechanical degradations and the other material degradation which is responsible for the changes in the mechanical properties of the disordered materials.