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 Fe 1−x Cux alloys at concentrations x from 0.06 to 0.4 at.% and temperatures T from 290 to 450 • C 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 Fc 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 ≤ 0.2%, the STN and the KMC results for the nucleation barrier Fc 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, x hom l (T ) and x het l (T ), and both dependencies are found to be rather sharp.

Introducing ab initio based neural networks for transition-rate prediction in kinetic Monte Carlo simulations

“…Having been thoroughly investigated in the literature [20,29,32,[53][54][55][56][57][58], the FeCu system is well suited for the evaluation of the quality of this DFT-ANN approach, evidencing both its potential benefits and limitations. It can potentially provide an efficient and reliable tool for migration-barrier prediction in KMC simulations as well as in other modeling techniques, while ensuring the best possible transfer of the multifold properties of the alloy, even though the DFT properties can sometimes be affected by uncertainties.…”

Atomistic modeling of radiation damage in crystalline materials

“…This method is computationally efficient but less accurate in modeling complex interactions between defects, particularly interstitial clusters, because of the possibility of multiple transitions. AKMC [91,92] is used for on-lattice simulations where all atoms are present in the system. This works when the defects being modeled are vacancies because the atomic structure stays close to a lattice configuration when an atom is removed.…”

Моделирование методом Монте-Карло кинетики распада и образования выделений на границах зерен общего типа в разбавленных ОЦК-сплавах Fe-Сu

“…Для моделирования распада исполь-зовались методы различного масштабного уровня: метод фазовых полей [15,16], статистическая стохастическая теория [17,18], метод Монте-Карло [19,20]. Широкое рас-пространение получило использование комбинирован-ных подходов, сочетающих атомистическое моделирова-ние и ab initio расчеты [21,22], обеспечивающие коррект-ную параметризацию свободной энергии и межатомных взаимодействий в зависимости от магнитного состояния матрицы Fe.…”