The effect of aging on the fracture behavior of Cu-AI-Ni jo phase alloys

The beneficial effect of aging on the intergranular embrittlement of the shape memory Cu-AI-Ni β phase alloys is described. The fracture progressively changes from completely intergranular to transgranular when quenched samples are aged. The change in fracture behavior appears to be associated with the precipitation of a ductile phase (a) in the grain boundary region. This hypothesis is supported by the results of electron microprobe analysis and Auger electron spectroscopy. Aging does not have any significant effect on the microhardness of samples. Some transmission electron microscopic observations of the changes occurring on aging are also presented. Formerly with The University of Connecticut, Storrs, CT 06268.