异 质 熔 丝 增 材 制 造 多 材 料 构 件 研 究 进 展（特 邀）

Significance Multi-material components, which effectively integrate the intrinsic properties of distinct constituent materials, hold immense promise for cutting-edge applications in high-value sectors such as aerospace, marine engineering, and nuclear energy. At present, the fabrication of such components still relies heavily on conventional joining processes including fusion welding, brazing, diffusion bonding, and mechanical fastening. Thus, the lack of exploration and development of novel, high-efficiency, and reliable techniques for the integrated forming of multi-materials has emerged as a core bottleneck restricting technological breakthroughs in the high-end equipment manufacturing industry. As a cutting-edge branch of additive manufacturing (AM), heterogeneous wire-based AM technology—defined as the use of two or more distinct materials—offers a novel avenue for the fabrication of multi-material components. The core principle of this technology lies in the precisely coordinated delivery of two or more dissimilar material wires into a molten pool during the deposition process; this enables accurate modulation of the chemical composition of the deposited layer by tailoring the wire feed rate ratio. On the one hand, the technology facilitates the direct, integrated joining and forming of multi-material components in a single fabrication step. On the other hand, it pioneers innovative manufacturing paradigms for the in-situ synthesis of advanced materials and the construction of compositionally continuous gradient structures. Collectively, it is poised to provide a new methodological framework and development direction for the processing and preparation of multi-metal components. Progress Heterogeneous wire-based AM technology boasts distinctive advantages including low production cost, high material utilization efficiency, and exceptional flexibility in compositional and structural design, rendering it a promising candidate for a disruptive manufacturing technology in the fabrication of multi-material components. Researchers worldwide have carried out extensive investigations into the multi-material deposition capabilities of this technology, thereby establishing a robust theoretical foundation and technical repository for the manufacture of high-performance multi-metal components. This study begins by reviewing the principles and equipment of heterogeneous wire-based AM technology. It elucidates the operating principles of multi-material wire-based AM technology under three typical heat sources—namely laser, electron beam, and arc—while introducing the deposition process characteristics and resultant sample properties for each heat source (Fig. 2). Subsequently, the review focuses on multi-metal components and interface control in heterogeneous wire-based AM. It covers the latest research progress on various heterogeneous material systems, including Inconel 825-SS316L, TC11-TA15, and SS316LSi-ER70S-6, as well as investigations into multi-material samples with innovative structures. Additionally, this paper details common interface regulation techniques and the fabrication of continuous gradient samples, highlighting the unique advantages of this technology. Simultaneously, the paper further elaborates on research regarding molten pool in-situ synthesis and process control for heterogeneous materials. It provides an in-depth analysis of the root causes of key challenges: complexities in the multi-wire feeding process, instabilities in the droplet metallurgical behavior, and the dynamic, time-varying nature of the molten pool metallurgical process. Corresponding countermeasure studies aimed at addressing these challenges are also summarized. Finally, the paper discusses the existing technical bottlenecks of heterogeneous wire-based AM and outlines its future development trends. Conclusions and Prospects This study reviews the latest research progress in heterogeneous wire-based AM technology for multi-metal components. It elaborates on the principles and equipment of this technology, as well as recent research findings regarding direct multi-material sample fabrication, interface regulation, and deposition process control. Furthermore, against the backdrop of multi-metal component manufacturing, the paper clarifies the future development directions of this technology while addressing key challenges in compositional resolution, compositional design, and process stability.