Additive manufacturing of functional gradient materials: A review of research progress and challenges

Functional gradient materials (FGMs) are composite materials made up of two or more materials, with components or structures that gradually change, resulting in a gradual change in performance and functionality. Additive manufacturing (AM) technologies have the potential to greatly benefit the development of FGMs by enabling efficient production of complex-shaped parts. The preparation and characterization of gradient alloys produced by AM, including metal-metal, metal-ceramic, ceramic-ceramic, and metal-organic, are discussed in this paper. An overview of the solutions and countermeasures for challenges encountered during FGM preparation is presented in this paper. These challenges include the generation of intermetallic compounds, the mismatching of thermophysical parameters, and the variation of the dilution rate across different gradient layers. Finally, potential areas for future research are outlined based on a summary of existing research. This work provides vital guidelines for future fabrication of FGMs.