Research progress on additive manufacturing of refractory high entropy alloys

The rapid progress in aerospace engineering places an urgent demand for advanced structural materials that exhibit outstanding mechanical properties under ultra-high temperature operating conditions. While recently developed refractory high-entropy alloys (RHEAs) hold promising application prospects, they are still confronted with challenges, including room-temperature brittleness and elemental segregation, which present significant hurdles in manufacturing processes. Additive manufacturing (AM) technology offers distinct advantages in fabricating RHEAs, such as suppressing elemental segregation, refining microstructures, and enabling the production of components with complex geometries, thereby revealing the substantial research potential. This paper firstly introduces the main technical methods for AM-fabricated RHEAs. Subsequently, it systematically summarizes their microstructural features, elemental distribution patterns, and phase composition characteristics, along with an overview of their mechanical performance at both room and elevated temperatures. To address critical process challenges, such as cracking and porosity in AM-produced RHEAs, we not only review recent research achievements but also propose innovative strategies that combine composition optimization and grain boundary engineering to enhance the AM process. Finally, this paper makes prospects for further enhancing the room-temperature plasticity and high-temperature strength by introducing grain boundary strengthening elements or high-entropy ceramic strengthening phases through additive manufacturing technology in the future, as well as for the preparation of large-sized RHEAs complex components by suppressing cracking and residual stress.