RECRYSTALLIZATION OF UNIDIRECTIONALLY SOLIDIFIED NI3AL DEFORMED IN TENSION

Behaviour and mechanisms of recrystallization at grain boundaries were investigated on stoichiometric Ni3Al which was unidirectionally solid ified by a floating zone method. Two specimens were deformed in tensio n to the two strains of about 0, 17 and 0.28, and then were annealed a t 1173 K for 3.6 x 10(3) s and 7.2 x 10(3), respectively. Recrystalliz ed grains were formed by two kinds of mechanisms preferentially along the grain boundaries. The strain induced boundary migration (SIBM) mec hanism can operated where dislocations with edge components impinged a nd piled up against the grain boundary. The other is the (111) rotatio n mechanism along the grain boundary where dislocations with screw com ponents impinged and piled up. These results are similar to those in a luminum and copper, especially copper bicrystals.