Effect of aluminum content on dislocation loops in model FeCrAl alloys

Highlights: • Dislocation loop average size decreased and volume number density increased with aluminum content. • The pinning effect of aluminum on dislocation loop is due to its atomic size mismatch for host atom. • The critical content of aluminum to inhibit the formation of a<100> dislocation loop is around 4 wt%. -- Abstract: Five kinds of iron-chromium-aluminum (FeCrAl) alloy samples with different contents of aluminum (Al)—Fe-12Cr, Fe-12Cr-2Al, Fe-12Cr-4Al, Fe-12Cr-6Al, and Fe-12Cr-8Al—were designed and prepared. All samples were then irradiated with 200 keV argon ions (Ar²⁺) to the fluence of 9.3 × 10¹⁴ ions cm⁻² at 330^°C. The formations of dislocation loops induced by Ar²⁺ irradiation in these alloys were investigated by transmission electron microscopy. Both of a/2<111> and a<100> dislocation loops were generated in all samples. The sizes of both a/2<111> and a<100> dislocation loops decreased and total volume number densities increased with increasing Al content of the samples. The proportion of a/2<111> dislocation loops decreased first and then increased with Al content, and the ratio of a/2<111> to a<100> average loop size increased first and then decreased with Al content. The experiment results indicate that the increase of Al content in alloys can enhance the nucleation and inhibit the growth of dislocation loops, the interaction between a/2<111> and a<100> dislocation loops is affected by the Al content in alloys as well. The difference in dislocation loops in FeCrAl alloys with different Al contents after Ar²⁺ irradiation can be explained by the pinning of dislocation loops by the Al atoms.