Abstract
Void lattices of various degrees of perfection have been observed in nickel-aluminum solid solutions containing up to 8 at.% Al irradiated by nitrogen ions at 500°C to doses up to 70 dpa. The void lattices are FCC and oriented parallel to the host lattice. The perfection of the void lattice is best in the 2% Al alloy, and becomes increasingly imperfect as the Al content increases. The ratio of the void lattice parameter to the average void "radius" was generally between 10 and 15, with a tendency to increase with increasing Al content. Void ordering was not observed in pure Ni irradiated under identical conditions. Void ordering was studied using standard quantitative metallographic procedures, but some preliminary experiments using optical diffraction were conducted. The visibility of the void strongly influences the optical diffraction patterns, the best results being obtained from out-of-focus bright-field electron micrographs. The role of solute segregation on the formation of the void lattice is discussed. It is suggested that solute segregation enhances the tendency for voids to nucleate non-randomly in the presence of existing voids. © 1978.