Quenched-in vacancies in Fe-Al alloys with Al content ranging from 24 to 49at% were investigated employing two complementary techniques of positron annihilation: slow positron implantation spectroscopy and positron lifetime measurements. It was found that quenched alloys exhibited a very high concentration of vacancies. Although the free positron component cannot be resolved in positron lifetime spectrum in majority of samples, the concentration of quenched-in vacancies could be still determined from the positron diffusion length measured by a variable energy positron beam. The lowest concentration of vacancies was found in a stoichiometric Fe3Al alloy. The concentration of defects increased with increasing degree of non-stoichiometry with respect to Fe3Al, i.e. in alloys with sub-stoichiometric and super-stoichiometric Al concentration. However, the increase in concentration of quenched-in defects was more pronounced in Al-rich alloys, i.e. alloys containing more than 25at%Al.

Quenched-In Vacancies in Fe-Al Alloys. O.Melikhova, J.Cizek, F.Lukac, I.Prochazka, J.Kuriplach, W.Anwand, G.Brauer: Journal of Physics - Conference Series, 2011, 262[1], 012039