The effects of segregation of solute atoms and vacancies on migration of a/4<111> and a/2<100> antiphase domain boundaries in stoichiometric Fe3Al at various temperatures were studied using a phase-field model based on the Bragg–Williams approximation and kinetic parameters determined from experimental data. Boundary mobilities were measured from the boundary velocity of shrinking circular antiphase domains. In the case of a/4<111> antiphase domain boundaries, solute atmospheres follow the antiphase domain boundaries until the antiphase domains vanishes by shrinking to zero radius, and therefore the boundary mobilities were always smaller than the intrinsic boundary mobilities because of the solute-drag effect. The boundary mobility of a/4<111> antiphase domain boundaries could be enhanced by up to 60% by vacancy segregation. On the other hand, the boundary mobility of a/2<100> antiphase domain boundaries was enhanced by only a few per cent. The a/2<100> antiphase domain boundaries were observed to break away from the solute atmosphere during as the circular antiphase domain boundaries shrink. The boundary mobility increased by up to 40% associated with the breakaway, and becomes equal to the intrinsic boundary mobilities even though slight depletion and segregation of Al atoms remain ahead and behind the migrating boundary, respectively.

Effects of Solute and Vacancy Segregation on Migration of A/4<111> and A/2<100> Antiphase Boundaries in Fe3Al. Y.Koizumi, S.M.Allen, Y.Minamino: Acta Materialia, 2009, 57[10], 3039-51