A critical review of the refractory high-entropy materials: RHEA alloys, composites, ceramics, additively manufactured RHEA alloys

In this study, the traits, production methods, and applications of refractory high-entropy materials—including refractory high-entropy alloys (RHEAs), refractory high-entropy composites (RHE-Cs), and refractory high-entropy ceramics (RHE-Ce)—which are part of the broader category of refractory high-entropy materials with a wide range of applications, have been thoroughly examined and discussed. RHEAs have emerged as materials that exhibit superior properties, such as high melting temperatures, excellent temperature resistance, and high wear and corrosion resilience, in addition to high mechanical and fatigue strength. These attributes have made them extensively studied materials in recent times. The properties of RHEAs suggest their safe operation in challenging environments such as nuclear reactors, gas turbines, aerospace, and energy production. Among refractory materials, RHE-Cs stand out for their high strength and low density, showing significant potential for use in the automotive, aerospace, and space industries. Another group with a wide range of applications, RHE-Ce materials, is distinguished by their high-temperature resilience, high hardness, and low thermal conductivity, making them suitable for high-temperature environments. Refractory materials are generally fabricated using traditional techniques such as arc melting, powder metallurgy, and magnetron sputtering. In this study, along with traditional production methods, additive manufacturing techniques which have revolutionized the manufacturing field are discussed concerning their applications in refractory material production. Additive manufacturing methods enable the achievement of high temperatures and the production of homogeneous, single-phase solid solutions, making them suitable for fabricating refractory materials with high melting points.