SURFACE RECRYSTALLIZATION IN A Ni3Al BASE SINGLE CRYSTAL ALLOY IC6SX

The specimens of a Ni_3Al base single crystal alloy IC6sx were cold worked by grit blasting and then heat treated in the temperature range of 800-1260℃for 1 h to 10 h.The ex- perimental results showed that the initially recrystallized nucleation temperature was about 1000℃and the primal recrystallization completing temperature was between 1200-1210℃.It has been found that the recrystallized grain size increased significantly with increasing temperature.However, the thickness of recrystallized layer almost kept 10μm in the temperature range of 1200-1240℃for 1 h,and increased fast to about 23μm in the temperature of 1260℃for 1 h.The results indicated that,different from the recrystallized behavior in most common Ni-based superalloys,the recrystal- lized grains in the interdendritic region grew faster than in the dendritic core.It was observed that a cellular transformation formed in the interface between recrystallized grain and the dendritic core.