Interfacial characteristics of Nickel-based hybrid structures fabricated using directed energy deposition

Abstract

The wire-arc directed energy deposition technique was used to develop nickel-based hybrid structures or to repair conventional structures of nickel-718 superalloy. Three different cases were investigated: deposited IN718 and IN625, separately, over the conventional IN718 substrate and deposited IN718 over the previously deposited IN625 substrate. The interfacial characteristics with respect to the microstructural features, residual stresses, compositional changes, etc., were studied using a finite element computational framework and a Monte-Carlo grain growth model. The numerical results were successfully validated with the experimental results. All the hybrid structures revealed excellent interfacial bonding with no defects, as evidenced by the failures outside the interface during their tensile tests. However, the interfacial characteristics differed for each material condition. The results discussed in this study will improve the understanding of developing nickel-based hybrid structures using additive methods and can potentially be beneficial in repairing industrial components.