The relation between enbrittlement and structural relaxation of an amorphous metal

Abstract

The ductile-to-brittle transition temperature of a Fe79.3B16.4Si4.0C0.3 glass, determined by performing bend tests at different temperatures, has been observed to shift continuously with increasing annealing. This shift can be correlated with the change in enthalpy due to structural relaxation, measured by differential scanning calorimetry. The correlation can be described by a simple phenomenological model, based on the change in free volume during relaxation and a minimum free volume for ductility. This glass remains entirely homogeneous during the annealing treatments, and surface crystallization has been ruled out as a cause of brittle fracture. © 1990 Taylor & Francis Ltd.