Entropy of kink pair formation on screw dislocations: an accelerated molecular dynamics study

Abstract

The Gibbs energy ΔG kp(τ, T) of kink pair formation on screw dislocations in bcc Nb has been determined as a function of shear stress τ at different temperatures T ≤ 100 K using an accelerated molecular dynamics method and a bond-boost potential. From ΔG kp(τ, T), the stress dependence of the entropy and the enthalpy of kink pair formation could be obtained using standard thermodynamic relations. The entropy of formation increases with increasing shear stress, following a phenomenologically predicted τ 1/2 dependence.