A model of the viscous-brittle transition upon fracture of metals and alloys

A model of the viscous-brittle transition upon fracture of metals and alloys that is based on the competition of the processes of microcrack development and dislocation generation is proposed. Micropores which occur in the region of stress concentration in the coagulation of vacancies are regarded as defects of one or another type. The kinetics of development of a micropore and the micropore-assisted generation of microcracks or prismatic dislocation loops are estimated quantitatively. The temperature dependence of the embrittlement of metals and alloys and also the influence of the loading rate and doping on the embrittlement temperature are considered.