Conservative climb motion of a cluster of self-interstitial atoms toward an edge dislocation in BCC-Fe

Abstract We have developed a model for the conservative climb motion of a hexagonal self-interstitial atom (SIA) cluster that is under the influence of the stress field of a nearby dislocation. The parameters required for the calculations were derived by molecular simulations of body-centered-cubic Fe. Using these parameters, kinetic Monte Carlo simulations were conducted to simulate the absorption process of an SIA cluster through the conservative climb to an edge dislocation that has the parallel Burger vector. The velocity of the conservative climb was found to be proportional to the inverse square of the distance between the cluster and dislocation, which is the same dependency observed in a previous analysis. However, the absolute value of the velocity strongly depends on the number of extra atoms or vacant sites that inherently exist on the edges of the cluster, because they enhance the formation of another defect pair that will induce the conservative climb. The activation energy for the conservative climb is much higher than the activation energy for pipe-diffusion of an atom along the edge of the cluster, although the latter is an elementary process of the former. The velocity of the conservative climb is nearly proportional to the inverse eighth power of the cluster size. Both of these findings are significantly different from those of the elasticity analysis.