Effect of temperature and stacking fault energy on the hardening of FCC crystals

A model to account for the temperature and stacking fault energy in the hardening of FCC metal single crystals is presented. Temperature and stacking fault energy are considered to affect primarily the cross-slip rate and the obstacle strength given by the forest dislocation. The essential experimental features are captured by the model. For high symmetry loading axes, the stress—strain curves for all temperatures show a similar initial high hardening slope, followed by a parabolic hardening. The initiation of the parabolic hardening is dictated by the temperature as shown in the experiments. For low symmetry loading, the extent of stages I and II, the hardening slope and the initiation of stage III are functions of temperature. The higher the temperature, the shorter the extent of stages I and II and the lower the hardening slope and the stress at the initiation of parabolic hardening. On the other hand, a high stacking fault energy reduces the extent of stages I and II and the levels of latent hardening, in keeping with the experimental observations.