Microstructure and mechanical property of Al,Ti co-adding L21-strengthened NiCrFe-based HEAs

In this study, leveraging on the machine learning, a novel high-strength Ni100-x-yCr25Fe25AlxTiy (x = 5, y = 5; x = 8, y = 7; x = 10, y = 10) high-entropy alloy (HEA) system was rationally designed, whose phase transformed from FCC + BCC to single BCC. The structural features, mechanical properties, and strengthening mechanism were systematically investigated. It has been discovered that the addition of Al and Ti can accelerate the for-mation of L21 phase. The Ni35Cr25Fe25Al8Ti7 HEA shows outstanding comprehensive mechanical behavior, whose yield strength, compressive strength, fracture strain, and nano-hardness is 1913.69 MPa, 3896.62 MPa, 39.94%, and 11.07 GPa, respectively. These findings will give new insights into the controllable design of novel high-performance HEAs, enabling the achievement of target microstructures and superior combinations of properties.