Dislocationless sliding in a polycluster glass

Abstract

Abstract At low temperature, T → 0, the yield stress of a perfect crystal is equal to its so called theoretical strength. The yield stress of imperfect crystals is controlled by the stress threshold of dislocation mobility. A non-crystalline solid has neither the ideal structure nor gliding dislocations. Its yield stress depends on the distribution of local critical stresses attributed to each atomic site at which the local inelastic deformation occurs. We describe the exactly solvable model of planar layer strength and sliding with an arbitrary homogeneous distribution of local critical stresses. The kinetics of thermally-activated creep of the sliding layer is described. The sliding activation volume scales with the applied external stress as ∼ωe -β, where β < 1. The proposed model accounts for mechanisms of the low temperature deformation of polycluster metallic glasses, since intercluster boundaries of a polycluster metallic glass are natural sliding layers of the described type. We also discuss applicability of the model to the low temperature plastic deformation of nano-crystalline materials.