Compositionally complex coherent precipitation-strengthened high-entropy alloys: a critical review

The coherent precipitation-strengthened high-entropy alloys (CPS-HEAs) as a new type of structural materials are expected to possess many unique mechanical properties, such as the outstanding strength-ductility combination at cryogenic and room temperatures. Apart from this, most of their strengths can even be well retained at elevated temperatures. The compositionally complex matrix and nanoprecipitation phases, as well as the coherent interfaces between them, can potentially bring novel merits of these CPS-HEAs, including sluggish diffusion, excellent thermal stability, and controlled magnetic properties. Note that the ductile coherent L1₂-nanoparticles can improve the strength of alloys without too much reduction of plasticity, while the coherent B2-nanoparticles strengthened HEAs display completely brittle failure upon tensile test at room temperature. An overview of the alloy design, microstructure evolution, oxidation resistance, mechanical and magnetic properties of CPS-HEAs are briefly discussed here. The advantages of multicomponent coherent precipitation-strengthened HEAs as well as the limitations in this field are also summarized. In addition, this review also points out the future research directions and prospects. Graphical abstract: [Figure not available: see fulltext.].