The effects of TiC particle on microstructure and mechanical properties of Inconel 718 fabricated by selective arc melting

Adding titanium carbide reinforcement particles into Inconel 718 matrix is considered to be an effective way of further improving the mechanical properties of Inconel 718 components fabricated by selective laser melting (SLM). However, SLM-fabricated TiC/Inconel 718 composite components typically exhibit the pore defects caused by poor wettability between the matrix and the TiC particles, which attributed to the low heat input of laser during deposition. A powder bed based additive manufacturing method using arc plasma as heat source, named selective arc melting (SAM), was developed in previous study by the authors. Significantly higher heat input from the arc heat source contributes to inhibiting the generation of pore defects in TiC/Inconel 718 composite components during SAM. In this paper, thin-walled parts of Inconel 718 and TiC/Inconel 718 composites were first fabricated by the SAM method. Then, the deposition geometry, microstructure, tensile properties and hardness of as-fabricated Inconel 718 and TiC/Inconel 718 composites components were systematically studied and compared. Results showed that a large number of dispersed carbides and fine equiaxed grains were observed in the TiC/Inconel 718 composites. Most of the added TiC particles were melted and the Inconel 718 matrix bonded well to the carbide precipitation phases. The TiC/Inconel 718 composite part exhibited better surface quality, tensile strength, ductility and hardness than that of Inconel 718. The combined effects of precipitation strengthening and fine grain strengthening were the main reasons for the better mechanical performance of the TiC/Inconel 718 composite part.