A relatively simple theoretical model, based upon the concept of the kink-pair mode of escape of screw dislocations trapped in Peierls valleys, was developed in order to account for the observed temperature dependence of the critical resolved shear stress, τ, and of the associated activation volume, v, in crystals with a high intrinsic lattice friction at rather low temperatures. In this model, the critical resolved shear stress varied with temperature T, as τ½ = A-BT. The associated activation volume, v, depended upon the temperature T, as v-1 = C-DT, where A, B, C and D were positive constants. Moreover, the activation volume, v, was found to be a function of τ, such that vτ½ was constant for a given slip system. Data analysis of the temperature dependence of the critical resolved shear stress of W, α-Fe, Cr and V crystals revealed excellent agreement between theory and experiment in both regime-III (low temperature or high stress) and regime-II (intermediate temperature and stress). However, the predicted temperature and stress dependences of the activation volume were confirmed by experiment in regime-II, but lacked quantitative agreement in regime-III.

Kinetics of Flow Stress in Crystals with High Intrinsic Lattice Friction. M.Z.Butt: Philosophical Magazine, 2007, 87[24], 3595-614