A new model of solution hardening in fcc metals based on the interaction with plural obstacles

Abstract

A new model of solution hardening in fcc metals assumes that dislocation motion is controlled by a thermal activation process. In the model, the interaction of a dislocation with plural solute atoms is taken into account in a single activation event. The actual number of solute atoms which are involved in an activation event is determined by minimizing the activation energy. The model predicts a temperature dependence for the flow stress that agrees reasonably well with experimental results. Especially, it predicts the appearance of an inverse temperature dependence of the flow stress in the low-temperature region. Thus, the anomalous lowering of the flow stress at low temperatures, observed in some dilute alloys, can be explained solely by the dislocation–solute atom interaction. This is to be compared with the conventional explanation, in which another cause, the so-called inertial effect, was invoked. Another feature of the new model is that it provides a simple explanation for the occurrence of the stress equivalence phenomenon.