Hot deformation behaviour and grain refinement of intermetallic compound Ni3Al

The paper describes the preparation of Ni3Al-based intermetallic compounds and investigations of their structures in the as-cast, worked, and annealed states. The performed experimental works approved a possibility of hot working of the highly brittle polycrystalline intermetallic compound Ni3Al with large grain cast structure. The facility of originating the recrystallization seems to be surprising in such a material. On the other hand, the growth of recrystallization nuclei is strongly retarded. The case is further complicated by the fact of heterogeneous deformation in the microvolume. Microalloying with boron or zirconium influenced the original structure parameters as well as the optimum deformation temperature. Simultaneously the probability of a transgranular cleavage fracture increased. For the stoichiometric Ni3Al intermetallic compound the optimum deformation temperature 1150 degrees C has been assessed. At temperature 1250 degrees C, the alloy Ni3Al + 0,1 at. % B manifested the best plasticity. The special type of rotary working combined with friction heating gave the best results from point of view of obtaining a fully recrystallized region.