Heterogeneous interfaces of aluminum bronze/Inconel 718 dissimilar alloys under different wire arc directed energy deposition sequences

Abstract

The layer-by-layer deposition strategy of additive manufacturing makes it ideal to fabricate dissimilar alloy components with varying functionality, which has promising application potential in a large number of industrial areas. In this study, two components composed of ERCuAl-A2 aluminum bronze (CuAl9) and Inconel 718 nickel-based superalloy were fabricated with different deposition orders by wire-arc directed energy deposition (wire-arc DED). Subject to changes in heat input and thermophysical properties of substrate, the transition region of the deposited Cu-Ni component with the bottom half of CuAl9 and the top half of Inconel 718 is narrow and serrated with a laminated intermetallic compound layer due to the convection and rapid cooling in the molten pool, while the Ni-Cu component deposited in the opposite order exhibits a 2 mm gradient transition zone due to the multi-layer partial remelting, in which a large number of diverse precipitates were found as well as regional variations in grain size. Both two components show strong bonds and their tensile specimens tested along the vertical direction always fracture at the softer CuAl9 side. Excellent tensile properties along the horizontal direction were obtained for Cu-Ni (Ultimate tensile strength: 573 MPa, yield stress: 302 MPa, elongation: 22 %), while those of Ni-Cu are much lower due to the existence of the solidification cracks in the transition zone. The results from this study provide a reference for the additive manufacturing of Cu/Ni dissimilar alloy components, as well as their microstructure and mechanical properties control.