| Ultrafine-grained materials, having grain sizes in the submicrometer or nanometer range, may be readily produced by processing bulk solids through the application of severe plastic deformation (SPD) and this leads to the possibility of revealing different flow mechanisms when these materials are tested at elevated temperatures. Experiments show the two-phase Zn-22% Al alloy and various magnesium alloys exhibit excellent superplastic properties after processing by SPD whereas it is not possible to reveal different creep mechanisms in high-purity aluminum because the ultrafine grains are unstable at high temperatures. |
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