Effects of segregation of solute atoms and vacancies on migration of antiphase boundaries in stoichiometric (Fe-25at%Al) and Al-rich (Fe-28at%Al) Fe3Al at 673K were studied using a phase-field method in which local vacancy concentration was taken into account. Boundary mobility of antiphase boundaries having different phase-shift vectors of a/4<111> and a/2<100> (hereafter denoted as B2 antiphase boundary and D03 antiphase boundary, respectively) was evaluated by measuring the boundary velocity of shrinking circular antiphase boundaries. Similar effects of the segregation on the migration of B2 antiphase boundaries were observed in both compositions. Vacancies segregated and Al-atoms were depleted at B2 antiphase boundaries in both compositions. Vacancy concentration at B2 antiphase boundaries was up to 80% higher than that in the bulk. As a result, the migration of B2 antiphase boundaries was greatly enhanced by the vacancy segregation. In contrast, the segregation to D03 antiphase boundaries showed a marked composition dependence. Vacancies were depleted and Al-atoms segregated at D03 antiphase boundaries in the Al-rich Fe3Al, whereas vacancies segregated and Al-atoms were depleted at D03 antiphase boundaries in the stoichiometric Fe3Al. The Al segregation in the Al-rich Fe3Al decreased mobility of D03 antiphase boundaries much more significantly than the Al-depletion in the stoichiometric Fe3Al. As the antiphase boundaries shrank, D03 antiphase boundaries broke away from the segregation atmospheres and the mobility increased rapidly in both compositions. A greater increase in the mobility due to the breakaway was observed in the Al-rich Fe3Al than in Fe3Al with the stoichiometric composition.

Effects of Solute and Vacancy Segregation on Antiphase Boundary Migration in Stoichiometric and Al-Rich Fe3Al - a Phase-Field Simulation Study. Y.Koizumi, S.M.Allen, M.Ouchi, Y.Minamino: Intermetallics, 2010, 18[7], 1297-302