Inconel 718-W7Ni3Fe bimetallic structures using directed energy deposition-based additive manufacturing

Abstract

Bimetallic structures produced via additive manufacturing (AM) have demonstrated outstanding potential for improving the properties of high-temperature structures. To this end, it was hypothesised in this study that using a tungsten alloy would increase the thermal conductivity of the bimetallic structure compared to pure Inconel 718. Bimetallic structures of Inconel 718 and W7Ni3Fe were manufactured using directed energy deposition (DED)-based AM. Hardness, thermal analysis by diffusivity measurement, and compression testing were done to evaluate the effect of tungsten alloy deposition on Inconel 718's thermal and mechanical properties. Bimetallic structures of Inconel 718-W alloy containing a 50–50 volume % of each displayed a 100% improvement in thermal diffusivity compared to pure Inconel 718, with extensive mixing and remelting due to laser processing. Furthermore, the bimetallic compression samples showed a 100% increase in yield strength combined with a 50% reduction in modulus of elasticity compared to Inconel 718.