THE TEMPERATURE-DEPENDENCE OF THE ANTIPHASE BOUNDARY ENERGY OF A RELAXED FAULT IN AN FE3AL ALLOY

In-situ annealing experiments in the transmission electron microscope have been carried out by examining superdislocations in a deformed Fe3 Al alloy. The separation of the superdislocation partials increases qu ickly at each annealing temperature studied to reach a new equilibrium value characterizing the relaxed state of the antiphase boundary. The extent of order relaxation at the boundary is greater than that takin g place throughout the ordered lattice but is much less than found in other studies on trialuminide alloys. It is suggested that the composi tion range over which a single-phase ordered material is retained will affect the extent of relaxation occurring. Consequently, in the case where the ordered composition range is narrow, the precise alloy stoic hiometry will affect the extent of relaxation.