Emdadi, A.; Yang, Y.; Bolz, S.; Stryzhyboroda, O.; Tovar, M.; Gein, S.; Hecht, U.; Weiß, S.: Mechanisms of necklace recrystallization in a BCC Fe-Al-Ta alloy with strengthening Laves phase precipitates. Scripta Materialia 237 (2023), p. 115705/1-6
10.1016/j.scriptamat.2023.115705
Open Access Version
Abstract:
A necklace structure composed of fine grains formed by dynamic recrystallization was uncommonly observed at the pre-existing grain boundaries during the hot compression of a BCC Fe-25Al-1.5Ta alloy containing C14 - (Fe, Al)2Ta Laves phase precipitates. Two possible mechanisms for necklace formation were proposed; particle-stimulated nucleation and grain boundary bulging, depending on whether the original grain boundaries are occupied by C14 particles, or they are free of them. Recrystallization was initiated preferentially around the clusters of large particles at the boundaries containing particles. In contrast, the bulging of the original grain boundaries by strain-induced boundary migration was observed as a preliminary stage for necklace formation at the particle-free boundaries. The necklace structure expanded into the deformed volume in such a way that low-angle subgrain boundaries decorating the necklace layers transformed into grains with increasing deformation strain.