On the effect of the layer thickness in Laser-Powder Bed Fusion of pre-mixed Incone1718-Cu powders

The customization of material characteristics in combination with extreme design flexibility represents the most intriguing scope of Additive Manufacturing. In this context, this work investigated the feasibility of the Laser-based Powder Bed Fusion process (L-PBF) of pre-mixed Inconel 718-Cu powder blends, exploring the effects of the laser-related process parameters and Cu addition, in order to develop alloys able to combine excellent mechanical properties under severe operating conditions with good thermal and electrical conductivity. More specifically, this work investigated the effects of using a layer thickness of $\boldsymbol{30 \mu \mathrm{m}}$ on the process quality in terms of density, microhardness, microstructure and surface roughness. Results showed that cubic samples with 10 mm side were successfully produced, with a relative density always greater than 98 percent. The resulting microhardness was from 290 to 340 HV, decreasing as a function of the Cu addition and keyhole defects development. The latter were the main defects observed in the microstructure, characterized also by heterogeneous crystalline grains for all the investigated conditions. Finally, the surface roughness (Sa) was from 7 to $\boldsymbol{25 \mu \mathrm{m}}$ , in line with the typical values of L-PBF products.