SUPERPLASTICITY IN A HIGH STRENGTH POWDER ALUMINIUM ALLOY WITH AND WITHOUT SiC REINFORCEMENT.

The superplastic properties of a rapidly solidified, high strength P/M Al alloy and the same alloy reinforced with SiC particulates (SiC//p) have been studied. To prepare superplastic test materials, a matrix alloy powder of composition 7. 2Zn-2. 4Mg-2Cu-0. 2Zr-0. 12Cr-0. 2Co (Kaiser PM-64) and the powder mixed with 10 to 20 vol pct SiC//p (approximately 5 mu m diameter) were thermomechanically processed to very fine equiaxed grain structures of approximately 6 mu m and approximately 8 mu m, respectively. Superplasticity in these materials was evaluated by characterizing (1) high temperature stability, (2) dynamic grain growth, (3) strain rate sensitivity, (4) flow stress behavior, (5) cavitation and cavitation control, and (6) total superplastic strain. It was observed that the PM-64 alloy could achieve a total elongation of over 800 pct, while the SiC//p reinforced alloy could attain an elongation greater than 500 pct before failure.