Microstructure characteristics of warm spray additively manufactured Inconel 718 superalloys and correlation with mechanical performance

This study focuses on Inconel 718, one of the most popular Ni-based superalloys for extreme environments, with high demand for in-situ repair and additive manufacturing. Highly dense Inconel 718 was solid-state deposited using warm spray (WS) without expensive and non-renewable helium. The role of nitrogen flow rate as a key factor in controlling the particle temperature was investigated to illustrate that lowering the nitrogen flow rate facilitates particle deformation, thus reducing surface roughness and densifying the Inconel 718 deposits. Another benefit is cost savings. Like cold spray, the larger the particle deformation, the more pronounced the process hardening (manifested as higher hardness); however, heat treatment can eliminate it effectively. The presented technique has great potential for high-quality and low-cost solid-state deposition of hard-to-deform metallic materials.