Integrated analytical and experimental study to determine optimal LPBF process parameters for Ni-10wt%TiCN composites

Abstract This study focused on determining the optimal laser powder bed fusion process parameters for fabricating pure nickel (Ni) reinforced with 10 wt% titanium carbonitride (TiCN). Using a response surface methodology (RSM) approach, the process parameters of laser power and scanning speed were systematically optimized to achieve the best combination of high relative density and hardness. The optimal parameters of 195-W laser power and 400 mm/s scanning speed yielded a relative density of 99% and hardness of 335 HV 0.5 which is an increase of 106% of the hardness of pure Ni. A porosity volume ratio of 0.23% and pore sphericity between 0.5 and 0.8 were calculated using computed tomography analysis. The fine pores were homogenously distributed. Microstructural analyses showed that while the majority of the TiCN particles remained unmelted, partial dissociation into the Ni matrix was observed without the formation of new phases. The TiCN particles facilitated nucleation leading to grain refinement and improved hardness. The refined microstructure consisted of both columnar and equiaxed grains elongated along the build direction, while in the perpendicular direction, it predominantly featured equiaxed sub-grains with a few sub-dendrites. The enhanced properties achieved make the composite suitable for applications requiring improved mechanical performance of high Ni content alloys, where its inherent properties are currently limited.