| Numéro |
J. Phys. Colloques
Volume 48, Numéro C3, Septembre 1987
4th International Aluminium Lithium Conference
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|---|---|---|
| Page(s) | C3-285 - C3-291 | |
| DOI | https://doi.org/10.1051/jphyscol:1987332 | |
J. Phys. Colloques 48 (1987) C3-285-C3-291
DOI: 10.1051/jphyscol:1987332
GRAIN REFINEMENT AND SUPERPLASTICITY IN A LITHIUM-CONTAINING Al-Mg ALLOY BY THERMOMECHANICAL PROCESSING
S.J. HALES, S.B. OSTER, B.W. SANCHEZ et T.R. McNELLEYMaterials Engineering Group, Department of Mechanical Engineering, Code 69, Naval Postgraduate School, Monterey, CA 93943-5000, U.S.A.
Abstract
The refined microstructures and superplastic properties resulting from controlled thermomechanical processing of an Al-8Mg-0.5Li-0.23Zr alloy were evaluated. Rolling between the solvus temperatures for Mg and Li in the alloy allowed for grain refinement by precipitation of β (Al8Mg5) during deformation and subsequent precipitation of δ' (Al3Li) on cooling. Increasing the rolling strain enhance the superplastic ductility of the alloy at 573K in the strain-rate regime of 10-3-10-2 S-1. Elongations in excess of 500 pct. , without cavitation, and a corresponding strain-rate sensitivity coefficient of approximately 0.5, were obtained. TEM investigations of the microstructural characteristics responsible for the mechanical behavior revealed that a more uniformly refined grain structure (3-5µm) evolved by continuous recrystallization (CRX) in material experiencing the larger rolling strain.