It was argued that the Peierls stress for dislocations in pure metal crystals was negligible. The resistance to dislocation motion was not quasi-static, but viscous. Direct observations of the viscous behaviour were cited, together with internal friction measurements. The measured viscosity coefficients were very small (less than mPas). It was pointed out that the yield points of pure metals were not associated with Peierls stresses but with the interaction of the stress dependences of dislocation velocities and the kinetics of dislocation multiplication. The negligible values of the stresses required to move dislocations were rationalized in terms of the small dependence of the cohesive energies of simple metals upon their atomic structures.

The “Peierls Stress” for Pure Metals (Evidence that it is Negligible). J.J.Gilman: Philosophical Magazine, 2007, 87[35], 5601-6