Wire-Based Additive Manufacturing of Multi-Material Structures: A Review

Multi-material structures have great potential in high-end fields such as aerospace and energy. Which integrate the advantages of various metals and meet the demands of complex working conditions. Among additive manufacturing technologies for multi-material structures, wire-based processes have become a research hotspot due to their high material utilization, low cost, and high efficiency. This article systematically reviews the progress of research on this technology. The working principles and characteristics of common heat sources (WAAM, LWAM, EBAM) are introduced. Furthermore, the advantages and limitations of these heat sources for manufacturing multi-material structures are critically analyzed. Moreover, various metal wire combination systems (such as steel/Ni, Al/steel, Ti/Al, and Cu/Ti, etc.) were reviewed, and the differences and influences of different wire feeding methods and directions were discussed. The review highlights research findings on microstructure regulation, interfacial bonding mechanisms, and the mechanical property optimization of polymetallic structures. The influence laws of critical process parameters on structural properties are also elucidated. The existing problems in the current research were pointed out, and the future development trends were prospected. Unlike previous articles, this review establishes a more comprehensive process–structure–performance framework through the discussion of integrated heat source characteristics, wire feeding systems, and interface adjustment strategies. It aims to provide references for promoting the development and engineering application of additive manufacturing technology for wire-based multi-metal structures.