In Situ Alloying through Laser-Powder Bed Fusion of a 60%Inconel718-40%Cu Powders Mixture

Abstract

Mixing elemental powders for the development of custom alloys with tailored properties represents one of the most intriguing contexts in the metal additive manufacturing field. With the aim to combine the properties of high-strength alloys and high thermal and electrical conductivity, this work relies on the experimental investigation of the Laser-based Powder Bed Fusion (L-PBF) process applied to a novel alloy obtained by pre-mixing, by means of a fluidized bed, Inconel 718 powders with Copper (Cu) powders at a consistent percentage (40%). The powder blend was then employed as the feedstock for L-PBF and cubic samples were produced with a layer thickness of 30 µm. The results, investigated in terms of density, microstructure, Vickers microhardness, surface roughness and thermal conductivity, proved the viability of L-PBF process. Samples without visible defects and with a relative density always greater than 96% were produced, but with a Cu content 8% greater than the one expected. A compact microstructure was obtained, suggesting that a lower microhardness (268–275 HV) in comparison with pure IN718 was primarily dictated by the Cu addition. Finally, a surface quality in line with the typical L-PBF products and an increase in the thermal conductivity of about the 24% were observed.