Peierls Barrier of Screw Dislocation in bcc Iron at Finite Temperature

Abstract

The Peierls barrier of a screw dislocation in body-centered cubic iron at finite temperature is investigated by using the free energy gradient method. By using the empirical potential, the Peierls barrier is shown to decrease from 11.7 to 6.9 meV per unit length of the Burgers vector with temperature increasing from 0 to 300 K. The entropy term of the Peierls barrier is estimated to be 0.19 k_B, and the change of free energy, which is an entropic effect, is found to strongly depend on the local atomic configuration.