Microstructures and mechanical behaviour of bimetallic structures of tungsten alloy (90WNiFe) and nickel alloy (In625) fabricated by wire-arc directed energy deposition

This study reported the fabrication of bimetallic structures (BS) from tungsten alloy (90WNiFe) and nickel alloy (In625) via wire-arc directed energy deposition (DED)-based additive manufacturing (AM). Its microstructures and mechanical properties were investigated for three different heat input conditions: low (180A), medium (200A), and high (220A). The highest average ultimate tensile strength of 618 MPa was achieved in the low heat input condition, with an average elongation of 49%. Although the ultimate tensile strength of the produced BS is lower than that of 90WNiFe and In625 individually, its yield strength closely resembles that of In625 processed by wire-arc DED. Tensile samples from each heat input condition experienced different fracture locations and exhibited distinct fracture morphologies. It can be concluded that the bonding strength is attributed to the diffusion of chromium, nickel, molybdenum, and niobium from In625 into the γ-(Ni, Fe, W) binding matrix of the 90WNiFe substrate.