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

摘要

The Gibbs energy Delta G (kp)(tau, T) of kink pair formation on screw dislocations in bcc Nb has been determined as a function of shear stress tau at different temperatures T <= 100 K using an accelerated molecular dynamics method and a bond-boost potential. From Delta G (kp)(tau, 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 tau (1/2) dependence.