Additive manufacturing of high-strength Inconel 718 alloy through the addition of Ti2AlC MAX particles

Decreasing the content of detrimental Laves phase in additively manufactured Inconel 718 alloy is highly essential. In the present study, we introduce a novel approach to effectively suppress the precipitation of Laves phase. By ex-situ incorporation of Ti2AlC MAX particles, Ti2AlC/Inconel 718 composites with Ti2AlC volume fractions of 5% and 10% are successfully fabricated using the directed energy deposition (DED) technique. In comparison to the Inconel 718 alloy, the 10 vol.% Ti2AlC/Inconel 718 composite exhibits 70.9% higher yield strength, 39.1% higher ultimate tensile strength, and 61.4% higher hardness. A detailed microstructure examination confirms that the detrimental Laves phase, which is abundantly present in the inter-dendritic region, is replaced by in-situ formed (Nb,Ti)(C,N) and γ' particles with average diameters of 1.12 μm and 10 nm, respectively. Through non-equilibrium solidification process simulation, the suppression of Laves phase, in-situ formation of multi-scale precipitates, and the microstructural evolution due to Ti2AlC addition are illustrated at the mechanistic level. Conclusively, a theoretical model of Ti2AlC/Inconel 718 composite is developed to reveal its underlying strengthening mechanism. It is indicated that Ti2AlC/Inconel 718 composites possess the capability to be a next-generation high-end nickel-based alloy.