An atomistic study of deformation of amorphous metals

Abstract

The computer simulation of a shear deformation of a model monoatomic amorphous metal has been performed. The strain was applied incrementally, relaxing the structure at each step. The complete stress-strain curve was thus obtained. A large number of microscopic deformation events have been observed and analyzed using the description of the local atomic structure by the atomic level stresses. Although no temperature effects have been included in the present study the calculated stress-strain curve is in very good agreement with the stress-strain curves measured experimentally at or above room temperature. The common feature of these experiments and present calculations is, however, the homogeneity of the deformation. Hence, it is argued that fundamental microscopic deformation mechanisms are the same at low and high temperatures and the macroscopic differences arise owing to the strain localization in the former case. The regions of inhomogeneous atomic movement which results in plastic deformation, have not been found to be correlated with local density fluctuations in contrast with assumptions of the models based on free volume theory. They are, however, correlated with regions of high shear stresses, called τ-defects. These defects are formed during the deformation, are sustained by the applied stress and appear to act as stress concentrators in the vicinity of which a localized viscous flow develops. © 1983.