Effects of TiC content on microstructure and mechanical properties of nickel-based hastelloy X nanocomposites manufactured by selective laser melting

The nickel-based Hastelloy X (HX) superalloy is widely applied in the aerospace industry because of its exceptional oxidation resistance and various beneficial properties at high temperatures. HX-based nanocomposites manufactured by additive-manufacturing processes based on powder-bed fusion, such as selective laser melting (SLM), are expected to further enhance the material's mechanical and thermophysical performance. This paper systematically studies the effects of TiC nanoparticle content on the microstructure and tensile performance of SLM-fabricated HX nanocomposites. The results reveal that the microcracking that formed in pure HX was successfully eliminated in the fabricated nanocomposites when 1 wt% and 3 wt% TiC nanoparticles were introduced. The fabricated HX-3 wt.% (HX-3) TiC nanocomposite showed several TiC clusters and a much higher pore-volume percentage (0.15%) compared to the HX-1 wt.% (HX-1) TiC nanocomposite, in which this percentage was determined to be 0.026%. Compared to SLM-fabricated pure HX alloy, the HX-1 nanocomposite exhibited over 19% and 10% improvements in ultimate tensile strength and elongation to failure, respectively. A further increase in TiC content to 3 wt% was not found to further enhance the tensile strength but did result in a 10% loss in elongation to failure in HX-3 nanocomposite. These findings offer a promising pathway to employ SLM to manufacture both high-strength and high-ductility materials through the careful selection of nanoparticle materials and their content.