Laser-powder bed fusion in-process dispersion of reinforcing ceramic nanoparticles onto powder beds via colloid nebulisation

Functionally grading material composition in laser-powder bed fusion grants the potential for manufacturing complex components with tailored properties. The challenge in achieving this is that the current laser-powder bed fusion machine technology is designed to process only powdered feedstock materials. This study presents a multi-feedstock material printing methodology for laser-powder bed fusion. Utilising colloid nebulisation, tungsten carbide nanoparticles were successfully deposited onto powder beds of stainless steel 316L during the laser-powder bed fusion process. By this means, a controlled volume of tungsten carbide nanoparticles was uniformly dispersed onto powder beds under the inert processing chamber atmosphere. As a result, specimens printed with this methodology showed an increase in strength. Similarly, the colloid medium played an important role in the resulting microstructures. It led to the formation of consistent and stable meltpools and a strong crystallographic texture. Recommendations are given for the successful dispersion of higher volumes of nanoparticles. Additionally, insights into application prospects for material nebulisation in laser-powder bed fusion are presented and discussed. •A tungsten carbide colloid was successfully nebulised onto powder beds during the laser-powder bed fusion processing of 316L.•Colloid nebulisation ensured a uniform dispersion of tungsten carbide within the austenitic microstructure of 316L.•The 316L specimens were strengthened with tungsten carbide nanoparticles.