Molecular-dynamic simulation of atomic displacement cascades in FeCr alloy

Background. High-chromium ferritic-martensitic steels and austenitic steels are primary candidates to be structural materials for present nuclear reactors and future fusion power plants. Increasing demands to the material's ability to be used at high temperatures and radiation doses raise a problem of development of new radiation-resistant structural materials. Despite considerable experience in exploitation of such materials, the problems of providing reliable theoretical description and prediction of material's behavior under irradiation still remain a great challenge. Materials and methods. The simulation of atomic displacement cascades was performed using MD method in FeCr alloy with different Cr concentration. To describe the interatomic interaction the authors used a modified version of many-body interatomic potential, proposed by Caro et al. and well reproducing the mixing enthalpy curve in random ferromagnetic FeCr alloy. Results. The MD simulation was performed at 300 К for five alloys: FeCr ( Fe-5at.$\%$Cr, Fe-10at.$\%$Cr, Fe-14at.$\%$Cr, Fe-20at.$\%$Cr, Fe-25at.$\%$Cr ). The atomic displacement cascades are considered for the PKA of 10 and 20 keV. The obtained simulation results allowed to perform a quantitative analysis of produced radiation- induced defects and evaluate Cr concentration in interstitial configurations at the final cascade stage. The results of point defect clusterization induced by the primary radiation damage were obtained for alloys under consideration. Conclusions. The performed simulation revealed: 1) the number of radiation-induced defects formed at the final cascade stage for the selected displacement energies is almost independent of Cr concentration in initial matrix of the alloy; 2) Cr concentration in interstitial configurations is 1.6-2 times higher than the initial Cr concentration in the matrix. Increasing Cr fraction in the alloy results in a gradual decrease of Cr concentration in interstitials; 3) the part of clustered vacancies is almost equal (within errors in calculations) to the fraction of clustered interstitial configurations for all cases under consideration.