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Processability of Thin-Powdered Inconel X750 and TiC Metal Matrix Composite by Laser-Directed Energy Deposition
keywords:
powder rheology
nickel-base superalloys
metal matrix composites
l-ded
additive manufacturing
The processability of pure Inconel X750 and Inconel X750 mixed with 15% vol. of titanium carbide particulate through laser Directed Energy Deposition (l-DED) was evaluated. The powders used had a particle size in a range unusual to l-DED processing (0.18 µm to 24.05 µm), this case study presents the difficulties in processing a thin quadri-modal powder and describes possible measures to mitigate them, while also reporting, likely for the first time, on the l-DED processing of Inconel X750 and such related MMC. The choice in reinforcement particle size and composition aimed for a reduction in material density and insertion of additional reinforcement mechanisms. Both powders used were analysed in an FT4 rheometer and compared to a reference Inconel 625 powder. l-DED was made viable, but results show that the powders tested here represent a lower limit for the rheological properties accepted by usual l-DED systems. A methodology to quantify the stability of a given processing condition is presented and validated, indicating also that low powder flows are recommended when processing powders of this sort. Inconel X750 demonstrated sensibility to oxidation during processing as depletion of Nb and Ti was detected in the deposits. Nor the MMC, nor the pure material cracked or showed excessive porosity. Microstructural characterization of non-heat-treated materials also showed microsegregation of Nb and Ti and a slight degradation of the added particulate.