Characterization of Inconel 625/TiC composite fabricated by Laser Powder Bed Fusion

The aerospace field has made significant progress in the last decades, making it necessary to develop materials with higher mechanical performance. For instance, Jet engines require high-temperature properties, and Ni-based superalloys are excellent candidates for this purpose. Because of the difficulties encountered in obtaining complex-shaped components, additive manufacturing (AM) offers new horizons to create near-net-shaped components with a high level of reliability. Laser powder bed fusion (LPBF) is one of the most mature AM techniques, and it is widely used for an ever-increasing number of materials. Inconel 625 is one of the most manufactured Ni-based superalloys with LPBF techniques, thanks to its high weldability. It presents extreme corrosion and oxidation resistance (up to around 1000 °C) coupled to good properties at elevated temperatures until 650°C. However, the fabrication of composites made of Inconel 625 alloy can produce higher mechanical performance than Inconel 625 alloy, making these composites an attractive candidate for the aerospace field. In particular, to improve the high-temperature properties, it is possible to modify the Inconel 625 alloy by adding ceramic particles obtaining a metal matrix composite (MMC). One of the best candidates for the purpose is titanium carbide (TiC), a refractory material with a high melting point and exceptional hardness, which seems to have good adhesions with Inconel 625. In this thesis, 1 wt. % of TiC micro-powders were added to Inconel 625 powders to obtain a TiC/IN625 composite by laser powder bed fusion (LPBF). The process parameters to obtain dense composites were determined. In detail, using higher energy with respect to the production of IN625 alloy, it is possible to obtain full densification with a relative density close to 100 %. Afterward, the microstructure of the as-processed and various heat-treated composites was compared to the base alloy in the same conditions. Finally, the mechanical properties were also evaluated and compared to the base alloy. The reinforcement enhanced the hardness as well as increased the temperature necessary for recrystallization with respect to the base alloy.