In-cascade interstitial cluster formation in concentrated ferritic alloys with strong solute-interstitial interaction: a molecular dynamics study

Molecular dynamics simulations of displacement cascades up to 40 keV have been performed using an EAM potential that mimics Fe-Cr alloys, by favouring interstitial configurations containing solute atoms. Both pure α-Fe and Fe-10 at.%Cr alloys were studied. The interstitial population at the end of the cascade was analysed from the standpoint of clustered fraction and chemical nature of the interstitial atoms. For pure α-Fe the results obtained are comparable with previous work. Two are the main effects of the presence of a high concentration of solute atoms strongly interacting with interstitials. First, a large number of solute atoms in interstitial position, mostly isolated, are found, in a proportion far above the average solute concentration in the alloy. Secondly, interstitial clusters containing a fraction of solute interstitial atoms always larger than the average solute concentration in the alloy are produced and this solute aggregation inside clusters may be a thermal spike effect. However, the total number of interstitial atoms produced in the cascade and even the in-cascade interstitial clustered fraction do not appear to be significantly influenced by the presence of solute atoms in high concentration, possibly because the masses of Fe and Cr are very similar.