The influence of grain boundary segregation on the recrystallization behaviour of Alloy 92 without Re (Cr-8, Al-6.5, W-6, Co-5, Ta-3, Mo-1.5, $Y_2O_3$-1.1, Ti-1, C-0.05, Zr-0.15, B-0.01, Ni-Bal.) has been investigated. Differential thermal analyses(DTA) revealed that dissolution of γ′ ($Ni_3$(Al,Ti)) initiated at about 1052℃ and completed at about 116℃. It was also found the recrystallization temperature of the Alloy 92 without Re was about 1228℃. These results indicate that the recrystallization behaviour of this alloy is not directly related to the dissolution of γ′.
On the other hand, energy dispersive spectrometry analyses(EDS) have shown that the alloying elements segregated at grain boundaries play an important role in the recrystallization of the alloy
Especially, Mo-rich regions elongated in the direction of hot extrusion , acted as nucleation sites of recrystallization. Since the recrystallization preferentially occurred at the Mo-rich region, the grains were also elongated in the direction of extrusion by applying heat-treatment at above recrystallization temperature. Recrystallization behaviour in the Alloy 92 without Re was explained by the degree of the segregate of alloying elements at grain boundary compared with those in the grain.
