Exploiting tube high-pressure shearing to prepare a microstructure in Pb-Sn alloys for unprecedented superplasticity

Superplastic Pb-Sn alloys were produced via tube high-pressure shearing ( t-HPS), in a single step start-ing from elemental solid bulks. A Pb-40 wt% Sn alloy showed an exceptional superplastic elongation as high as similar to 1870% at a strain rate of 1.0 x 10 -3 s -1 at room temperature, thereby elevating the optimum strain rate for maximum elongation under these conditions by more than one order of magnitude over conventional cast Pb-Sn alloys. This unprecedented room temperature superplasticity is attributed to the equiaxed grains having uniform sizes of the order of one micrometer, and in particular to the well-mixed domains of Pb and Sn in nearly equal proportions. This microstructure cannot be attained in cast eutec-tic or hypoeutectic alloys through conventional thermomechanical processing, but instead it is a direct outcome of t-HPS-generated compositional patterning at room temperature. (c) 2021 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Automated summary

Superplastic Pb-Sn alloys with exceptional elongation were produced via tube high-pressure shearing (t-HPS) starting from elemental solid bulks. This unprecedented room temperature superplasticity is attributed to equiaxed grains and well-mixed Pb and Sn domains in nearly equal proportions.