Impact of TiC particles on the process window and temperature evolution during PBF-LB/M manufacturing of aluminum/TiC composites

Laser Based Powder Bed Fusion (PBF-LB/M) of particle-reinforced aluminum-matrix composites (AMCs) has the potential to combine the low density and high ductility of aluminum with the high strength and wear resistance of ceramics while enabling complex geometries. In this study, the fabrication of TiC containing feedstock material was achieved by a simple and economically attractive blending approach. The blend was processed in a PBF-LB/M machine to fabricate AMCs. This paper evaluates the impact of the TiC particles on the processability. With the addition of TiC, the reflectivity of the blend is reduced, but instead of an expansion of the melt pool size due to a higher energy input, a counterintuitive decrease of the melt pool dimensions occurs, indicating lowered melt pool peak temperatures. The root cause is a less efficient heat transfer to the aluminum powder, caused by shielding effects of TiC. These conclusions are supported by simulations and thermal imaging results. The investigations reveal that the effect of TiC particle addition is strongly dependent on particle size and content. While TiC microparticles facilitate processability, TiC nanoparticles deteriorate it. The results give insights into the PBF-LB/M processing of AMCs, and the gained knowledge can be transferred to other material combinations where ceramic nano- and microparticles are added to a metallic powder via a powder blending approach.