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Significance of High Rate Superplasticity in Metallic Materials

Published online by Cambridge University Press:  16 February 2011

Norio Furushiro  and
Shigenori Hori
Norio Furushiro
Affiliation:
Department of Materials Science and Engineering, Faculty of Engineering, Osaka University, 2-1 Yamadaoka, Suita Osaka, 565, Japan
Shigenori Hori
Affiliation:
Department of Materials Science and Engineering, Faculty of Engineering, Osaka University, 2-1 Yamadaoka, Suita Osaka, 565, Japan
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Abstract

It has been expected that “High rate superplastic materials” will be developed for industrial applications. The Dorntype equation for high temperature deformation suggests that strain rate can be increased if the grain size is decreased. This means that grain refinement can effectively establish high strain rate superplastic materials.

It is well known that a high degree of grain size refinement will result from the addition of zirconium to Al-base alloys. Powder-metallurgical processing with rapidly solidified powders is also available for the improvement of superplasticity by both the refinement of the solidified structure and the maintenance of the stable fine structure of a 7475 Al alloy during recrystallization and deformation. Therefore. P/M 7475 Al alloys containing Zr up to 0.9 wt% were selected as candidate specimens. The objective of the present paper includes the clarification of the role and the effective amount of Zr to obtain high strain rate superplastic materials. As a result, the addition of 0.3%Zr or more is effective in grain refinement of the P/M 7475 Al alloy. However, alloys containing 0.7 and 0.9 wt%Zr only show superplasticity at 793K. The optimum strain rate is shifted to a higher range with increasing Zr. The alloy of 7475 Al-0.9%Zr shows the maximum elongation of 900% at the remarkably high strain rate of 3.3×10−1 s−1.

The deformation mechanism of such high stain rate superplasticity will be discussed briefly, by considering the effect of the fine particles of Zr on superplastic behavior.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 196: Symposium T – Superplasticity in Metals, Ceramics, and Intermetallics , 1990 , 249
Copyright
Copyright © Materials Research Society 1990

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References

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