The ductile–brittle transition phenomenon

This chapter deals with the very important phenomenon associated with the brittle fracture or amorphous alloys and the structural relaxation phenomenon. In this phenomenon, on reaching a specific temperature of preliminary annealing T br within the range of stability of the amorphous state the amorphous alloys become brittle, completely or partially, at room temperature. This phenomenon of the loss of ductility of the amorphous alloy is not only of purely scientific but also considerable practical interest. It is the measure of relaxation processes in the amorphous alloys and the indicator of their thermal-time stability, and also restricts to a large extent the temperature range of the heat treatment of the industrial alloys. More accurate measurements show that the ductility of a ribbon of an amorphous alloy after such a sharp jump remains low but different from zero and there is a second stage of the jump-like decrease of ductility at a higher preliminary annealing temperature.