Point defects in FeAl

Summary Point defects in annealed B2-phase FeAl samples in the range 47–53 at.% Fe were studied using⁵⁷Fe M?ssbauer spectroscopy. Spectra were analyzed using local environment models according to which point defects in atomic shells close to probe atoms induce shifts in the nuclear monopole interaction. For well-annealed samples, better results were obtained assuming only the presence of Fe_Al antisite and V_Fe vacancy defects, and not of Al_Fe antisite defects. Monopole interactions of⁵⁷Fe probes on the Fe and Al sublattices having no defects in the first two shells were about +0.27 and −0.03 mm s⁻¹, respectively, with respect to Fe in alpha-Fe metal. The shifts induced by Fe_Al and V_Fe defects in the first shells of Fe probes on the Fe and Al sublattices were −0.15 and −0.24 mm s⁻¹, respectively, and, in the second shells, +0.06 and +0.011 mm s⁻¹. In addition to structural defects needed to accommodate deviations from stoichiometry, annealed samples were found to contain several percents of Fe_Al and V_Fe defects due to lattice disorder, with greater disorder in Fe-deficient alloys. Paper presented at the ICAME-95, Rimini, 10–16 September 1995.