Refractory metals and their alloys are promising structural materials for operation in elevated temperature environments ( \(\ge \) 1200 \(^{\circ }{\hbox {C}}\) ). Despite extensive historical research during the mid-twentieth century, challenges in achieving a balanced set of properties, including fabricability, oxidation resistance, and high-temperature strength, hindered broader implementation of this alloy class. Recently, modern interest in these materials has been renewed by the refractory multi-principal element alloy (RMPEA) design philosophy and new developments in processing pathways, such as additive manufacturing (AM), that could enable their production. This review provides a critical comparison of the historical and modern approaches to refractory alloy design and processing, highlighting the shared mechanisms between conventional refractory alloys and RMPEAs. Key areas discussed include deformation mechanisms at low, intermediate, and elevated temperatures; the importance of tractable processing pathways in the successful implementation of new materials; and design considerations for developing alloys for AM that are derived with insights from the welding literature. Knowledge gaps and critical challenges are identified, and opportunities are proposed to accelerate the development of next-generation refractory alloys.
