Local elasticity and macroscopic plasticity in homogeneous and heterogeneous bulk metallic glasses

To understand why heterogeneity leads to improved ductility in bulk metallic glasses (BMGs), we derived the local elastic moduli and energy barriers for the activation of shear transformation zones (STZs) in homogeneous and heterogeneous BMGs using high-energy x-ray diffraction. In contrast to the homogeneous glass, STZ activation dynamics in the heterogeneous BMG are spatially nonuniform and the activation of STZs with low energy barriers is favored. Using qualitative arguments, we propose that there is an alternative deformation pathway involving multiple shear bands, which makes the material plastically deformable.