Identical Al-Mg-Sc alloys without and with 0.034-wtT Sn additions were fabricated heat-treated, and tensile tested in a fine-grain (d<6 mu m) condition at four strain rates form 10~(-2) to 10~(-4) s~(-1) and at temperatures from 723K to 823K. Alloys with Sn additions exhibited reduced failure strains at 723K but higher failure strains at 823K for the slowest strain rates. The effect of Sn on flow stress, activation energy for flow stress, and strain rate exp9onent was explored and was found to be small. The main effect of Sn was suggested to be in reducing cavitation by allowing a redistribvution of stress at critical hetero-junctions in the alloys.
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