Additive Manufacturing of Refractory Alloy-based Multi-Material Structures: A Review

efractory alloys exhibit exceptional high-temperature strength and stability, but their high melting points and limited ductility restrict the fabrication of complex structures through conventional manufacturing methods. Additive manufacturing (AM) provides new opportunities by enabling geometric freedom, near net-shape capability, and the fabrication of multi-material structures. These attributes allow fabrication of compositionally graded interfaces, improved thermal stress management, and integration of diverse functionalities. However, AM of refractory alloy-based multi-material systems remains challenging due to non-uniform thermal gradients, oxidation, cracking susceptibility, vaporization of elements, and formation of brittle intermetallic compounds. Understanding the process-structure-property-performance relationship is therefore essential for predicting material behavior and optimizing process parameters. This review summarizes major AM processes for refractory alloys, examines strategies for multi-material design, and analyzes the microstructure-property relationships that govern mechanical performance. Key challenges and future research directions are highlighted, emphasizing the need for design rule establishment to enable reliable, next-generation high-temperature materials fabricated through additive manufacturing.