Additively manufactured metal matrix composites: a review of fatigue and creep resistance for in-service conditions
Metal additive manufacturing (AM) enables the fabrication of arbitrary three-dimensional structures with unprecedented design freedom. However, components must withstand extreme in-service conditions, including high temperatures, fatigue, and creep, necessitating materials with multifunctional properties. Metal matrix composites (MMCs), comprising reinforcing particles embedded in metallic matrices, offer promising solutions for such harsh environments. Nevertheless, the non-equilibrium nature of AM processes introduces complex phase diffusion, reactions, and melt flow dynamics, making microstructural design and production challenging. This review focuses on the fatigue and creep resistance of additively manufactured MMCs under in-service conditions, emphasizing how composite strategies influence these properties. The underlying mechanisms responsible for property enhancements via AM are interpreted and discussed. Key findings indicate that AM enables refined microstructures, improved particle dispersion, and the formation of in-situ reinforcing phases, which collectively enhance fatigue life and creep resistance. For instance, TiC-reinforced steels exhibit improved wear resistance after heat treatment, and boron-phosphorus interactions in Inconel 718 enhance creep properties. The review provides insights into future directions for developing AM MMCs for critical applications, highlighting the need for tailored microstructures and process optimization to achieve balanced mechanical performance.