The migration of point defects was studied in alloys with Al contents of 25 to 40at%. The equilibration process was monitored via the Doppler broadening of the 511keV positron annihilation peak, using a 22Na positron emitter. Annealing of the B2 and D03 structures led to the determination of effective migration enthalpies. Annealing a 25at%Al alloy with the D03 structure or a 40at%Al alloy with the B2 structure yielded single migration enthalpies of 0.45 and 1.2eV, respectively. Annealing a 30 or 35at%Al alloy revealed 2 recovery stages. In the 30at%Al alloy, an early recovery was associated with a migration enthalpy of 1.0eV, and a later recovery was associated with a migration enthalpy of 1.3eV. The equivalent results for a 35at%Al alloy with the B2 structure were 0.9 and 1.8eV. Those for a 35at%Al alloy with the D03 structure were 1.8 and 1.7eV.

Investigation of Point Defect Migration in Fe-Al Alloys by means of Fast Doppler Broadening Technique. B.Kohler, J.Wolff, M.Franz, A.Broska, T.Hehenkamp: Intermetallics, 1999, 7[3-4], 269-76