Nano-precipitates strengthened non-equiatomic medium-entropy alloy with outstanding tensile properties

In this work, a novel non-equiamotic Ni46Cr23Co23Al4Ti4 medium-entropy alloy (MEA) strengthened by nanoscale coherent gamma' particles with L1(2) superlattice was successfully synthesized, then its microstructure, mechanical properties, strengthening and deformation mechanism were systemically investigated. Our experimental results demonstrated that this precipitation strengthened MEA exhibited outstanding strength-ductility synergy, combination a high yield strength of similar to 920 MPa, an ultimate tensile strength of similar to 1320 MPa and an excellent ductility of similar to 36%. The nanosized gamma' particles bought out effective precipitation strengthening in this non-equiamotic MEA, contributing a majority yield strength enhancement of similar to 600 MPa. For this gamma'-strengthened MEA, the dominant deformation model was the stacking-faults controlled mode rather than the mechanical twin dominated mode in single-phase face-centered-cubic structure Ni50Cr25Co25 MEA. Our work provides a further understanding of precipitate strengthening in non-equiamotic high-entropy alloys (HEAs)/MEAs.