Multi-material deposition of Inconel 718 and Ti–6Al–4V using the Ti–Nb–Cr–V–Ni high entropy alloy intermediate layer

Multi-materials are required in high-tech industries that require different properties at different locations in the same structure. The successful utilization of multi-materials can be economical, space-saving, and easy to maintain in engineering applications. Regardless of the technique used, the multi-material deposition (MMD) of Ti and Ni alloys presents some unique challenges. In this study, MMD of Ti–6Al–4V and Ni–20Cr using a high-entropy alloy (HEA) intermediate layer was performed, and deposition failure causes were analyzed. Deposition failures were found to be caused by the immiscibility between materials, differences in thermal properties, and interface due to the formation of brittle intermetallic compounds (IMC). HEA causes lattice distortion owing to the difference in the size of the elements constituting the solid solution and has excellent mechanical properties owing to the lattice distortion and the unique microstructure caused by the formation of a single-phase solid solution. In addition, HEAs do not form IMC because they exhibit slow diffusion rates. Therefore, HEA could be used as an effective interlayer to inhibit IMC formation. In this study, Inconel 718 and Ti–6Al–4V were successfully deposited by applying a Ti–Nb–Cr–V–Ni HEA intermediate layer to MMD. In addition, microstructure analysis and hardness measurements were performed to analyze whether IMC inhibition and successful deposition occurred.