Defect Formation and Binding Energies in FeCr Alloys as a Function of Cr Concentration: A Simulation Study

Significant progress has been made in modelling the formation and stability of defects and clusters in Fe-Cr alloys as a function of chromium content. A new / version of the CDM potential can be used in the study of defects in Fe-Cr alloys. Vacancy formation energy shows a linear dependence with the concentration for concentrations above 6% between the vacancy formation energy in iron and the vacancy formation energy in chromium, while it is almost constant for smaller concentrations. Formation energies for <100>, <110> and <111> self- and mixed-interstitials converge to a unique value with Cr concentration independently of the starting geometry. <100> geometry is the more stable. A change in the stability of <110> interstitials is observed: Fe-Cr interstitial is more stable for concentrations below 5% Cr while Fe-Fe is the most stable for concentrations above 10% Cr. The <110> Fe-Fe interstitial formation energy shows a very weakly dependence on the Cr position. A strong dependency of the formation energy with the Cr position for the case of <110> Fe-Cr interstitials is observed and could be explained by the strong repulsion between the two Cr atoms at short distances. This is the same for the vacancy. The stability of vacancy clusters increases with the cluster size for the studied sizes (up to 5 units) and it slightly differs between both potentials for higher Cr concentrations. However binding energies are shown to be not dependent on the Cr concentration for both potentials. (author)