Mechanisms of inelastic deformation in metallic glasses

The phenomenology of inelastic deformation in metallic glasses is briefly reviewed. This is followed by a short review of methods used to characterize the glassy structure. Considerable emphasis is put on the amorphous soap bubble raft as a two-dimensional analog medium that can give quantitatively accurate simulations of both the structural properties ofmetallic glasses and the mechanisms of their inelastic deformation. Analysis of such sheared bubble rafts has established that the basic ingredient of inelastic deformation in these materials is shear transformations occurring in small, atomic size volume elements that are only weakly interacting. Through the use of an inter-bubble potential, the changes in energy of these shear transformations can be analyzed in great detail. This has disclosed a remarkable capability in the model to parallel and predict complex relaxation phenomena in metallic glasses down to the detail of simulating the distributed nature of the structure and the free energies for transformation. This has led further to a very satisfactory model for the kinetics of anelastic and viscoplastic response of the structure for processes on shear localization, and nas led even to a semi-quantitative model for embrittlement resulting from physical ageing.