Recrystallization and grain growth in a B2 iron aluminide alloy

Abstract

Abstract Recrystallization and grain growth were studied in hot extruded B2 FeAl by X-ray texture measurements and Orientation Imaging Microscopy (OIM). Asextruded material contained ultra-fine grains of 0.2–0.4 μm. Such grains contained high dislocation densities, but mostly possessed high angle boundaries with the immediate neighbors. Depending on the annealing conditions, a combination of fine equiaxed and/or large columnar grains was observed. The fine equiaxed grains were at least 10 times larger than the as-extruded grain size and contained lower dislocation densities—which points towards primary recrystallization. Large columnar grains were observed in samples with fast heating and/or prolonged annealing at higher temperatures and were possibly formed by grain growth. Samples with predominantly equiaxed grain structure contained a similar texture as in the as-extruded material—a strong [110] fiber. Formation of the large columnar grains reduced the [110], but increased the [111] fiber. Possible selection of [111] grains for grain growth is not due to grain size advantage, as grain size distributions of all three fibers were similar, but can be understood from the consideration of grain boundary character distribution (GBCD) or mesotexture.