Electron Beam Powder Bed Fusion of γ-Titanium Aluminide: Effect of Processing Parameters on Part Density, Surface Characteristics, and Aluminum Content

Gamma titanium aluminides are very interesting for their use in high-performance applications such as aircraft engines due to low density, high stiffness and favorable high-temperature properties. However, the pronounced brittleness of these intermetallic alloys is a major challenge processing through conventional fabrication methods. Additive manufacturing by means electron beam powder bed fusion (EB-PBF) significantly improves processability preheating temperatures facilitates complex components. The objective this study was determine suitable window EB-PBF TNM-B1 alloy (Ti-43.5Al-4Nb-1Mo-0.1B), using an increased aluminum content raw material compensate evaporation losses during process. Design experiments used evaluate effect current, scan speed, focus offset, line offset layer thickness on porosity. Top surface roughness assessed laser scanning confocal microscopy. Scanning microscopy, backscatter diffraction (EBSD) energy-dispersive X-ray spectroscopy (EDX) were microstructural investigation analyze loss depending volumetric energy density EB-PBF. An optimized process parameter set achieving part densities 99.9% smooth top surfaces derived. results regarding microstructures suggest solidification via β-phase.