Ultrahigh high-strain-rate superplasticity in a nanostructured high-entropy alloy.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 32483194.
- Also identified by DOI 10.1038/s41467-020-16601-1 and PMC identifier 7264233.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Superplasticity describes a material's ability to sustain large plastic deformation in the form of a tensile elongation to over 400% of its original length, but is generally observed only at a low strain rate (~10<sup>-4</sup> s<sup>-1</sup>), which results in long processing times that are economically undesirable for mass production. Superplasticity at high strain rates in excess of 10<sup>-2</sup> s<sup>-1</sup>, required for viable industry-scale application, has usually only been achieved in low-strength aluminium and magnesium alloys. Here, we present a superplastic elongation to 2000% of the original length at a high strain rate of 5 × 10<sup>-2</sup> s<sup>-1</sup> in an Al<sub>9</sub>(CoCrFeMnNi)<sub>91</sub> (at%) high-entropy alloy nanostructured using high-pressure torsion. The high-pressure torsion induced grain refinement in the multi-phase alloy combined with limited grain growth during hot plastic deformation enables high strain rate superplasticity through grain boundary sliding accommodated by dislocation activity.