GRAIN BOUNDARY STRUCTURE IN Ni3Al

The influence of boron segregation and non-stoichiometry on grain boundary structure in Ni3Al was studied by transmission and scanning electron microscopy techniques. Small angle twist and tilt boundaries were produced by hot pressing misoriented single crystals of both doped and undoped material. Dislocation structures were observed in both bicrystal and polycrystal grain boundaries. In most cases the grain boundary dislocations were found to have the expected a Burgers vector, however in one case dislocations with Burgers vector a/2 have been observed. Using a SEM diffraction technique the frequency of occurrence of grain boundary types was examined and found to be unchanged by the addition of boron