Progress in Metallurgical and Mechanical Aspects of Complex Alloying and Composite Systems in Metal Additive Manufacturing

The discovery of metal additive manufacturing (MAM) has caused a significant revolution across multiple industries, enabling the production of prototypes and high-quality products with the added benefit of tailoring microstructural features in real time. This breakthrough has opened up new possibilities for the development of highly functional products through the use of multi-material systems. Consequently, there has been a substantial increase in research focused on MAM in the last few decades, particularly in the areas of functionally graded structures (FGS), high-entropy alloys (HEAs), and metal matrix composites (MMCs). In response to the growing demand for additive manufacturing in multi-material systems, this comprehensive review aims to provide an up-to-date understanding of complex alloying systems and MMCs manufactured through powder bed fusion (PBF), wire-arc additive manufacturing (WAAM), directed energy deposition (DED), and binder jetting (BJ). Additionally, the article offers an initial exploration of phase evolution and property changes exhibited by standard alloying systems produced using MAM. Ultimately, this review concludes by addressing the barriers encountered while fabricating such complex alloying systems with MAM and proposing solutions to overcome them. Furthermore, the article presents valuable recommendations for future research opportunities in this evolving field. This review seeks to consolidate knowledge, foster innovation, and drive advancements in multi-material additive manufacturing systems.