Enhancement of Strength and Plasticity by Nanoprecipitation Strengthening and Stacking Fault Deformation in a High Entropy Alloy

Precipitation strengthening can effectively improve the strength of high entropy alloys (HEAs), but usually severely reduces the ductility. In this study, a new interstitial carbon-doped HEA with a nominal composition of Ni33.5(CoFe)55V5Nb5C1.5 at.% was developed. The HEA exhibits a high yield strength of 1244 MPa, ultimate tensile strength of 1553 MPa and excellent elongation of ~ 30%. The stacking fault energy of the matrix is affected by the precipitation of L12-Ni3Nb, which enhances the stacking fault (SF)-induced deformation. Since the Taylor lattice domains are subdivided by the SF networks, the mean free path of dislocation is reduced. The enhanced strain-hardening ability leads to a good combination of strength and ductility.