The ongoing need to develop more sustainable and lower-emission propulsion systems for aerospace and automotive industries has been attracting research interest in the field of titanium aluminide alloys for several decades. Titanium aluminides are characterized by high specific strength and stiffness as well as favorable high-temperature properties, while having a significantly lower density compared to the widely used nickel-based superalloys. One result of ongoing alloy development is the β-solidifying TNM™ alloy Ti-43.5Al-4Nb-1Mo-0.1B, also known as TNM-B1. Despite the good hot workability of this alloy above the brittle-to-ductile transition temperature (BDTT), conventional processing remains challenging due to the material's inherent brittleness. Additive manufacturing can be a viable alternative for the near-net-shape production of titanium aluminide components. Electron beam powder bed fusion (PBF-EB/M) is particularly suitable, as the high process temperatures enable processing above the BDTT and thus crack-free component manufacturing. In addition, the vacuum process atmosphere prevents oxygen pick-up.

In the literature, different parameter sets for processing a material with PBF-EB/M are often compared on the basis of the volumetric energy density. In this study, the influence of the individual process parameters (beam current, scan speed and line offset) on the resulting microstructure of TNM-B1 was systematically investigated, while keeping the overall volumetric energy density at a constant value. The obtained microstructure was examined by means of scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and micro-hardness measurements (HV0.05) with a special emphasis on microstructural homogeneity and process-induced aluminum evaporation. The results show that despite the overall constant energy input, significant differences in terms of the obtained microstructures can be observed.