Research Progress on Nanoprecipitation-Strengthened High-Entropy Alloys

Precipitation strengthening is considered as an effective approach to enhance the strength of high-entropy alloys (HEAs), and understanding of the precipitation mechanisms and the relationship between precipitate microstructure and mechanical properties is crucial for the development of high-performance HEAs. This article provides a comprehensive review of the research progress and future perspectives on nanoprecipitation-strengthened HEAs, with an emphasis on the influence of various types of precipitation, including coherent precipitation, incoherent precipitation, and co-precipitation, on the mechanical behavior and strengthening mechanisms of HEAs. Coherent precipitates can significantly strengthen the alloys while maintaining good ductility, benefiting from their excellent lattice matching and stress transfer with the matrix. Incoherent precipitates can provide high work hardening, but it is important to reasonably tailor their morphology, size, and distribution, and to fully utilize the excellent ductility and strain hardening capability of the matrix, in order to achieve a good strength-ductility balance in HEAs. Furthermore, the co-precipitation method can take the advantages of various types of precipitates, which opens new opportunities for optimizing mechanical properties of HEAs. Despite the great promise, nanoprecipitation-strengthened HEAs still face challenges in terms of thermal stability, elevated-temperature performance, and cost, which require further research efforts in the future. This review presents the recent advancement and key issues of nanoprecipitation-strengthened HEAs, which can provide useful guidelines for the development of advanced HEAs for technological applications.