Nanometre-scale defects in shear bands in a metallic glass

Abstract

Abstract We have compared the structure of shear bands with that of undeformed regions of a metallic glass. Using quantitative high-resolution electron microscopy, we observed void-like defects, approximately 1 nm in diameter and at a concentration of one in 100nm3, which are generated as a result of plastic deformation in the shear bands. These defects may result from the coalescence of excess free volume upon cessation of the flow. By comparing the free energy of the shear band containing uniformly distributed free volume with that of the relaxed shear band with voids present, we show that the coalescence is thermo-dynamically possible.