Point defects diffusion in pure Ni and binary nickel-based alloys: a kinetic Activation-Relaxation Technique (k-ART) study

Even for simple defects, such as point defects, details of the kinetic diffusion remains incompletely understood. Using the kinetic Activation-Relaxation Technique (k-ART), an unbiased off-lattice kinetic Monte Carlo method with on-the-fly catalogue building, we study point defects diffusion in pure nickel and binary nickel-based alloys known for their resistance to corrosion and good mechanical proprieties. K-ART allows us to construct an extensive description of the energy landscape surrounding various defects and obtain detailed information regarding the various activated mechanisms and diffusion pathways. In this talk, we present the most probable diffusion pathways for systems containing one to five vacancies and one to five self-interstitial atoms in pure nickel. For these systems we find diffusion rate is not monotonic with the number of defects, we also show that, for interstitial clusters, diffusion takes place from excited states. We then analyze the effect of alloying on these pathways, focusing in nickel alloys with copper, iron and aluminum.