Superplasticity of VCoCrFeMnNi high-entropy alloy processed by high-pressure torsion

Abstract

In this study, the superplasticity of nanostructured V10Cr15Mn5Fe35Co10Ni25 (at%) high-entropy alloy processed by high-pressure torsion was investigated using high-temperature tensile testing in the temperature range of 873–1073 K and strain rate range of 5.010−4 to 1.010−2 s−1. The alloy exhibited extreme elongation at these elevated temperatures, with the greatest elongation of 770% at 973 K without any necking or a notable cavity in the fracture area. Other impressive achievements were also recorded (700% elongation at 1073 K and 3.310−3 s−1 and 600% elongation under other conditions). The equiaxed microstructure was maintained in both the deformed and undeformed regions of the tensile specimen, demonstrating that grain-boundary sliding is a dominant mechanism of the present superplasticity. It was noted that the strain rate sensitivity was not high (0.29–0.34) due to some grain growth during the elevated temperature tensile tests.