High strain-rate superplasticity in a fine-grained PM 7475 Al Alloy

Superplastic behavior of powder-metallurgy (PM) processed 7475 +0.7Zr Al alloy having a fine grain size of 2 um was investigated. Strain-rate-change tests were conducted at elevated temperatures to examine the strain rate-stress relations. The deformation behavior was analyzed by assuming the presen...

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Bibliographic Details
Published in:Metals and materials (Seoul, Korea) Korea), 1998-01, Vol.4 (6), p.1133-1141
Main Authors: Kim, Woo-Jin, Kim, Jong-Kab
Format: Article
Language:English
Subjects:
Alloys
Aluminum base alloys
Deformation analysis
Deformation mechanisms
Elongation
Grain boundary sliding
Grain size
High strain rate
High temperature
Metallurgy
Plastic flow
Self diffusion
Short fibers
Superplasticity
Threshold stress
Whiskers (metals)
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Summary:Superplastic behavior of powder-metallurgy (PM) processed 7475 +0.7Zr Al alloy having a fine grain size of 2 um was investigated. Strain-rate-change tests were conducted at elevated temperatures to examine the strain rate-stress relations. The deformation behavior was analyzed by assuming the presence of threshold stress for grain boundary sliding. After the threshold-stress compensation, the plastic flow was found to correlated well with lattice self-diffusion in pure aluminum. A maximum tensile elongation of up to 1000% was observed at a very high strain rate near l0-1s-1 and 515°C. A deformation map was constructed to identify the dominant deformation mechanism for the PM alloy. It was the grain boundary sliding controlled by lattice diffusion in aluminum. Evidence of short fiber or whisker-like formation were observed on the fractured samples over a wide range of temperature.
ISSN:1225-9438
1598-9623
2005-4149
DOI:10.1007/BF03025987