Stress-strain relations in bulk metallic glasses and colloidal dispersions

A comparison is made between the nonlinear rheological response of bulk metallic glass formers and of colloidal dispersions. Stress-strain curves measured after switch-on of constant deformation rates are analyzed quantitatively using a schematic model of mode coupling theory generalized to homogeneous and incompressible flows. A mapping between metallic and dispersion rheology is possible when stresses are rescaled by an entropic scale, accumulated strains by geometrical factors, and rates by the intrinsic relaxation time. Exploiting this similarity and the possibility to directly observe individual colloidal particles, we investigate the structural distortions in the colloidal system using confocal microscopy. The distortions exhibit the (from elasticity theory) expected quadrupolar but also a strong isotropic component.