Laser powder bed fusion of WC-reinforced Hastelloy-X composite: microstructure and mechanical properties

Nickel-based superalloys such as Hastelloy X (HX) are widely used in gas turbine engines for their exceptional oxidation resistance and high-temperature strength. The addition of ceramic reinforcement further enhances these superalloys' mechanical performance and high-temperature properties. For this reason, this paper investigates the microstructure and mechanical property of laser powder bed fusion (LPBF) additively manufactured HX-1 wt% WC (tungsten carbide) composite specimens. The results demonstrate that the LPBF-fabricated composite was observed to have several pores and microcracks, whilst only pores were detected in the as-fabricated pure HX. Compared to the fabricated pure HX, the tensile yield strength of such HX composite parts was increased by 13% without undue sacrifices to ductility, suggesting that the very limited number of microcracks were not sufficient to degrade the mechanical performance. The significantly increased dislocations were considered to be the primary contributor for the mechanical performance enhancement in the LPBF-fabricated composite material. The findings offer a promising pathway to employ LPBF process to fabricate advanced microcrack-free composites with high-strength through a careful selection of ceramic reinforcement materials.