In-situ synthesized duplex core–shell heterostructures in hypoeutectic Ni–W medium–heavy alloys: a strategy for ultrahigh strength

This study in-situ synthesized a duplex core–shell heterostructure in hypoeutectic Ni–W alloys, which enhanced yield strength from 637 MPa to 1989 MPa (212% increase) and achieved a substantial strain of 19.6%. This innovative core–shell heterostructure was created by alloying molybdenum (Mo) into the Ni–42W–10Co matrix. During heat treatment, the inter-dendritic regions transformed into hard ε-martensite, while the dendritic regions retained a soft austenite structure. The hard ε-martensite shell contributes significantly to high strength, while the soft austenitic core enhances plasticity. These microstructural features interact synergistically, resulting in an alloy with both superior strength and excellent plasticity.