Enhancing mechanical properties of NiCoCr-based medium entropy alloys by tuning multiscale heterogeneous structures

Enhancing mechanical properties of NiCoCr-based medium entropy alloys by tuning multiscale heterogeneous structures

In this project, we aim to design novel NiCoCr-based medium entropy alloys (MEAs) and further enhance their mechanical properties by tuning the multiscale heterogeneous composite structures. This is being achieved by alloying of varying elements in the NiCoCr matrix and appropriate thermal-mechanical processing.

NiCoCr ternary medium entropy alloy (MEA) attracts considerable attention due to its excellent mechanical properties (including tensile strength, ductility and fracture toughness) at room and cryogenic temperatures. These properties are even superior to those of quinary FeCoNiCrMn high entropy alloy (HEA). Considering its single face-centered cubic (FCC) structure which ensures the substitutional solid solution strengthening, the mechanical properties could be further enhanced by introducing additional strengthening mechanisms via alloying with other elements and/or microstructural tuning. This has been confirmed by our preliminary results that the tensile strengths (both yield and ultimate) of the newly designed NiCoCr-based MEA with multiscale heterogeneous structures are significantly higher (≥300MPa) than the reference NiCoCr alloy with similar ductility.

Annealing twins, stacking faults and nano-particles in an aged MEA.

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