Negative mixing enthalpy approach for advanced multi-component alloys: a perspective for high strength yet ductile alloy development
Jiaqi Meng, Xuefei Chen, Zibing An, Yi Liu, Yonghao Zhao, Hao Zhou, Xiaodong Han
Abstract
In high-entropy alloys (HEA), mixing entropy governs element distribution, while mixing enthalpy dictates interatomic interactions, influencing the formation of solid solutions or intermetallic compounds. Negative mixing enthalpy emerges as a pivotal factor in achieving high yield strength and ductility by driving local chemical fluctuations, short-range ordering, and second-phase formation, thereby optimizing the microstructure. However, excessive negativity in mixing enthalpy can trigger a brittle fracture in metallic materials during tensile deformation, reducing mechanical performance. To optimize HEA design, we propose: (1) introducing controlled ‘negative enthalpy genes’ to promote SRO via non-equilibrium heat treatments; (2) balancing strength and ductility by fine-tuning enthalpy negativity; and (3) innovating heat treatment techniques to prevent brittle intermetallic growth. These strategies provide a transformative approach to strengthening and toughening M/HEAs, encourage deeper fundamental research to unlock their full potential for advanced material applications.