Void Morphology In NiAl

Abstract

ABSTRACTVoid formation in stoichiometric NiAl was studied through controlled heat treatments and transmission electron microscopy. Voids formed at temperatures as low as 400°C, but dissolved during annealing at 900°C. Both cuboidal and rhombic dodecahedral voids were observed, often at the same annealing temperature. At higher annealing temperatures (>800°C) extensive dislocation climb was noted. The relative incidence of void formation and dislocation climb can be related to the mobility of vacancies at each annealing temperature. Further, differences in void shape can be described in terms of their relative surface energy and mode of nucleation.