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

Abstract

The Gibbs energy ΔGkp(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 ΔGkp (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.