Studies of homogeneous precipitation in very dilute iron–copper alloys using kinetic Monte Carlo simulations and statistical theory of nucleation

Abstract

Kinetics of homogeneous nucleation and growth of copper precipitates under electron irradiation of FeCu alloys at concentrations from 0.06 to 0.4 at.% and temperatures from 290 to 450C is studied using the kinetic Monte Carlo (KMC) simulations and the statistical theory of nucleation (STN). The conventional assumption about the similarity of mechanisms of precipitation under electron irradiation and during thermal ageing is adopted. The earlier-developed model of interactions in Fe–Cu alloys is used for both the KMC simulations and the STN calculations. Values of the nucleation barrier and the prefactor in the Zeldovich–Volmer relation for the nucleation rate are calculated for a number of concentrations and temperatures. For the dilute alloys with , the STN and the KMC results for the nucleation barrier do virtually coincide with each other, which seems to confirm a high reliability of the STN for this problem. The STN calculations are also used to estimate the temperature dependencies of concentrations which correspond to the homogeneous or the heterogeneous precipitation limit, and , and both dependencies are found to be rather sharp.