Analysis on Nucleation of a Dislocation Loop in a Magnesium Single Crystal -Approach from Atomistic Simulations-
Masayuki URANAGASE, Sana KAMIGAKI and Ryosuke MATSUMOTO
Abstract:We performed atomistic simulations to demonstrate the nucleation of a dislocation loop for the basal and prismatic slips of a magnesium single crystal. The dislocation loop was successfully simulated by employing the constrained molecular dynamics method, which involves constraining the atomic motion above and below the activation site, keeping the distance between the domain centers constant in the slip direction. Then, the activation free energy for nucleation of a dislocation loop was evaluated using the thermodynamic integration method and the dependence of this nucleation on the ambient temperature and applied shear stress was studied. Moreover, we compared the activation free energy of nucleation from a free surface to that of homogeneous nucleation in order to investigate the effect of inhomogeneity on the activation free energy. Key Words:Magnesium, Constrained molecular dynamics, Dislocation nucleation, Thermodynamic integration, Activation free energy