Recrystallization behaviors of FGH98 alloy

The precipitated phase behavior, microstructure characteristics and static recrystallization mechanisms of FGH98 alloy in extruding and annealing states were systematically investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). A portion of recrystallized grains were observed in as-extruded samples during the cooling process, and the dislocation density decreases with the increasing of deformation temperature. The recrystallization mechanism of FGH98 alloy during the annealing process is mainly dominated by residual primary γ' phase. In the region with a more content of residual primary γ' phase, static recrystallization is controlled by the coalescence and growth of subgrains;when residual primary γ' phase in the alloy decreases, many nucleation mechanisms of static recrystallization may occur, such as strain-induced boundary migration (SIBM), nucleation in the juncture of several grains, and twins superposition nucleation. It must be pointed out that residual primary γ' phase in the alloy can also be softened to somewhat extent by recovery and recrystallization during the annealing process.