Strengthening of a CrMnFeCoNi high-entropy alloy by carbide precipitation

The equiatomic CrMnFeCoNi high-entropy alloy (HEA) exhibits outstanding toughness and excellent strength-ductility combination at cryogenic temperatures. However, its strength is relatively low at room temperature. In order to strengthen this HEA, microalloying additions of 0.8 at.% Nb and C were made and its properties and microstructure evaluated. It was found that the microalloying resulted in the formation of carbide precipitates and a reduction of the grain size to similar to 2.6 mu m. As a result, the room-temperature tensile yield strength (732 MPa) of the microalloyed HEA is roughly double that of the base HEA (with a concomitant increase in the ultimate strength) while its ductility is maintained at a relatively high level (elongation to fracture of similar to 32%). The strengthening is due to precipitation hardening from the nanoscale carbide particles and grain refinement. Crown Copyright (C) 2019 Published by Elsevier B.V. All rights reserved.