| A study has been made of the superplastic behavior of a rapidly solidified AL-3Li-1Cu-0. 5Mg-0.5Zr(wt.%) alloy. Although rapidly solidified Al-Li alloys have the very fine grain structure desirable for the improved superplasticity, unfavorable oxide morphology often prevents them from being superplastic. The results of superplastic deformation indicate chat the proper thermomechanical treatment (TMT) of the alloy results in a much improved superplastic ductilities, e.g., elongat.ion of approximately 530%, in spite of the unfavorable oxide morphology. In the case of testing at. 520℃, optimum strain rate of forming is 4 × 10^(-2)/s, tvhich is one or two orders of magnitude higher than that of ingot cast Al-Li alloys. Such a high strain rate is thought to be quite advantageous for the practical application of superplastic deformation of the alloy. It can also he seen chat, the microstructure of the deformed specimens is similar to that in the as-received or the TMT conditions since continuous recrystallization is accomplished by subgrain growth and the growth of the primary grains is prevented by the fine β`(Al₃ Zr) particles. |
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