The Effects of Solutes on the Fracture Behavior of Metals

Abstract

A transition from ductile behavior at high temperatures to brittle fracture at low temperatures is characteristic of most metals of bcc or hcp structure. Alloying elements may either raise or lower the transition temperature by changing one or more of the following: grain size, deformation modes, distribution of impurity atoms, amount and distribution of second-phase particles, and strength of the crystal. Metals of fcc structure, while ordinarily not exhibiting a ductile-to-brittle transition, undergo brittle failure in the presence of corrosive environments and certain liquid metals. Alloying additions tend to increase the susceptibility to embrittlement in these cases, although the detailed mechanisms are not yet well established. These effects are discussed in terms of the Cottrell-Petch theory of fracture.