Kinetics of heterogeneous dislocation precipitation of NbC in alpha-iron

Abstract

We propose Monte Carlo simulations of the precipitation kinetics of NbC on dislocations in α-iron based on an atomistic description of the main mechanisms controlling the kinetic pathway. The algorithm takes into account realistic diffusion properties, with a rapid diffusion of C atoms by interstitial jumps and a slower diffusion of Fe and Nb atoms by vacancy jumps. A simple model of dislocation includes interactions with solute atoms, through local segregation energy and long range elastic fields. The relative importance of local segregation energies and long range elastic stresses on the precipitation characteristics, such as early segregation of carbon atoms on dislocations, transient precipitation of metastable carbides, and homogeneous and heterogeneous NbC precipitation, is discussed.