Thermal activation analysis of enthalpic and entropic contributions to the activation free energy of basal and prismatic slips in Mg

Abstract

The nucleation of a dislocation loop for basal and prismatic slips of a magnesium single crystal was studied via atomistic simulations. The metadynamics method was applied in order to overcome the time-scale restrictions that occur in conventional molecular dynamics simulations. The activation free energy of a dislocation loop nucleation is also evaluated via the metadynamics method. In particular, from the temperature dependence, we showed that a linear relationship between the enthalpic and entropic contributions to the activation free energy is satisfied. We found that the difference between the dependence of the activation free energy on the temperature for basal and prismatic slips is related to the structure of the $\ensuremath{\Gamma}$ surface.