Activation Energies of Plasticity and Lattice Properties of Cubic Crystal Systems

Abstract

The activation energy of diffusion-controlled dislocation climb of face-centred cubic metals and some intermetallic compounds can be traced back to G c a 0 3 , the product of an appropriate shear modulus G c and the third power of the lattice constant a 0 . This can be done by using a relationship connecting the climb energy with the Debye temperature, and by adopting a simple but precise law between Debye temperature and the elastic constants. A similar procedure can be performed for elemental and compound semiconductors, but the dependence of the climb energy on the Debye temperature and, consequently, on the elastic constants is different from that of the metal systems. In this case the climb energy turns out to be proportional to G c a 0 . Since for the semiconductors the activation energies of dislocation climb and glide are known to be correlated, such a relationship can be also applied to dislocation glide in these covalently bound materials. The latter results are discussed in terms of the kink mechanism and of the shuffle-set glide-set problem of dislocation motion in a Peierls potential.