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

TL;DR

This study combines kinetic Monte Carlo simulations and statistical theory to analyze homogeneous copper precipitation in very dilute Fe-Cu alloys under electron irradiation, revealing high reliability of the theoretical approach for dilute compositions.

Contribution

It introduces a combined KMC and STN approach to accurately model nucleation in dilute Fe-Cu alloys, validating the statistical theory against simulations.

Findings

STN and KMC results for nucleation barrier agree for x<0.2%.

Nucleation barriers and rates are calculated across various conditions.

Sharp temperature dependencies for precipitation limits are identified.

Abstract

Kinetics of homogeneous nucleation and growth of copper precipitates under electron irradiation of Fe_{1-x}Cu_x alloys at concentrations x from 0.06 at.% to 0.4 at.% and temperatures T 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 aging is adopted. The earlier-developed ab initio model of interactions in Fe-Cu alloys is used for both the KMC simulations and the STN calculations. Values of the nucleation barrier F_c and the prefactor J_0 in the Zeldovich-Volmer relation for the nucleation rate J are calculated for a number of concentrations and temperatures. For the dilute alloys with x less then 0.2%, the STN and the KMC results for the nucleation barrier F_c 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 both dependencies are found to be rather sharp.