Superplasticity in a high strength powder aluminum |
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Authors: | Murray W Mahoney Amit K Ghosh |
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Affiliation: | (1) Rockwell International Science Center, 1049 Camino Dos Rios, 91360 Thousand Oaks, CA |
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Abstract: | 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
(~5 μm diameter) were thermomechanically processed to very fine equiaxed grain structures of ~6 μm and ~8 μm, 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 SiCp reinforced alloy could attain an elongation greater than 500 pct before failure. Also, it was shown that with the use of
hydrostatic pressure during superplastic flow, cavitation could be controlled. Observations were made of the effect SiC
p
reinforcement particles had on the superplastic flow stress behavior. Interpretations are proposed to explain the role of
particulates during superplastic straining. |
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Keywords: | |
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