Equilibrium shape of dislocation shear loops in anisotropic α-Fe

We present dislocation dynamics (DD) simulations of shear loops in a highly anisotropic linear elastic crystal. The equilibrium shapes of the loops are determined for the four principal slip systems of the body-centered-cubic lattice, using empirical elastic constants for α-Fe, for a range of temperatures over which its elastic anisotropy varies considerably. The results are compared with those obtained from the isotropic elasticity approximation, and from an analytical line tension model. Sharp corners, which have been observed in the electron microscope and arise due to the thermodynamic instability of certain dislocation orientations, are reproduced by DD simulations in qualitative agreement with existing analytical calculations. Some differences are observed between the DD and the line tension model predictions.