Influence of magnesium on grain refinement and ductility in a dilute Al-Sc alloy

Furukawa, M., Utsunomiya, A., Matsubara, K., Horita, Z. and Langdon, T.G. (2001) Influence of magnesium on grain refinement and ductility in a dilute Al-Sc alloy. Acta Materialia, 49 (18), 3829-3838. (doi:10.1016/S1359-6454(01)00262-2).

Abstract

Experiments were conducted to determine the influence of magnesium additions on grain refinement and tensile ductility in an Al–0.2% Sc alloy processed by equal-channel angular pressing (ECAP). The experiments show ECAP reduces the average grain size to within the range of ~0.70 to ~0.20 ?m for alloys containing from 0 to 3% Mg but the as-pressed grain size increases to ~0.3 ?m in an alloy with 5% Mg because it is then necessary to use additional annealing treatments during the pressing process. The ultrafine grains introduced by ECAP are stable to high temperatures in the alloys containing from 0 to 3% Mg: in all alloys, the average grain size is <5 ?m after annealing for 1 h at temperatures up to ~750 K. High superplastic ductilities were achieved in the alloy containing 3% Mg but alloys containing 0.5% and 1% Mg exhibited the enhanced ductilities generally associated with conventional Al–Mg alloys. The results suggest the addition of ~ 3% Mg is optimum for achieving superplastic elongations at rapid strain rates in the Al–0.2% Sc alloy.

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Contributors

Author: T.G. Langdon

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