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Creep behavior of a cryomilled ultrafine-grained Al–4% Mg alloy

Published online by Cambridge University Press:  31 January 2011

R. W. Hayes ,
V. Tellkamp  and
E. J. Lavernia
R. W. Hayes
Affiliation:
Metals Technology Inc., 19801 Nordhoff Street, Northridge, California 91324
V. Tellkamp
Affiliation:
Department of Chemical and Biochemical Engineering and Materials Science, University of California, Irvine, California 92697–2575
E. J. Lavernia
Affiliation:
Department of Chemical and Biochemical Engineering and Materials Science, University of California, Irvine, California 92697–2575
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Abstract

The creep behavior of a cryomilled ultrafine-grained Al–Mg alloy was examined. The grain size ranged from 300 to 400 nm. The stress exponents ranged from 7.2 to 7.4. The apparent activation energy for creep, 83.7 kJ/mol at 27.5 MPa and 77 kJ/mol at 38 MPa, agreed well with the activation energy for grain boundary diffusion in aluminum. Transmission electron microscope analysis following creep at 300 °C to approximately 0.2% strain in 1411 h revealed the grain size was unchanged from its as-extruded size indicating significant thermal stability of this material at relatively high fractions of the melting temperature. The creep resistance of the Al–Mg alloy was rationalized in terms of an attractive interaction between grain boundary dislocations and incoherent particles within the boundary region, which suppressed grain boundary deformation. The grain boundary particles also led to high thermal stability by exerting a Zener pinning force on the grain boundaries, thus inhibiting grain growth at high temperatures.

Type
Articles
Information
Journal of Materials Research , Volume 15 , Issue 10 , October 2000 , pp. 2215 - 2222
Copyright
Copyright © Materials Research Society 2000

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References

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