Abstract: As the demand for high-strength materials at elevated temperatures grows, this study pioneers a novel approach to the high-temperature mechanical properties enhancement of Inconel 718 alloy, achieving this through the controlled reinforcement with titanium carbide particles (TiCp) via laser powder directed energy deposition (LPDED). Core-shell composite powders with varying TiCp content (1, 3, and 5 wt%) were prepared using the surface modification and reinforcement transplantation method. The LPDED-printed TiCp-added specimens, which were crack-free and homogeneous, exhibited a higher density compared to their pristine counterparts. Microstructural variations were observed in the as-built and heat-treated samples, which impacted the mechanical properties at room and high temperatures. Notably, the sample with a 3 wt% TiCp addition exhibited an exceptional yield strength at 800 °C, demonstrating a 40 % enhancement compared to its wrought Inconel 718 counterpart while also satisfying elongation requirements at room temperature. Through the analysis of the strengthening mechanism and investigation of mechanically tested samples at high temperatures, the strengthening enhancement is mainly induced by interstitial atom clusters near the dislocations and precipitates. This investigation underscores the modification of the microstructural and mechanical characteristics through TiCp control in LPDED, offering insights into the development of high-performance metal matrix composites for high-temperature applications.

Key words: Inconel 718, High-temperature strength, Mechanical properties, Metal matrix composites, Nano-structures, Laser powder-directed energy deposition