Laser Powder Bed Fusion of Ti-6Al-4V-XFe: Processability and Microstructure Analysis

Laser Powder Bed Fusion (L-PBF) is widely used in metal additive manufacturing (AM) to process titanium alloys, but controlling the microstructure of Ti-6Al-4V during solidification is still challenging. The rapid thermal cycles usually promote columnar prior-β grain growth and martensitic α′ formation, which can increase anisotropy and limit the as-built mechanical response. In this work, iron (Fe) was introduced as an in situ alloying element to evaluate its effect on the processability, densification, phase constitution, and microstructural development of Ti-6Al-4V-xFe alloys fabricated by L-PBF. Gas-atomized Ti-6Al-4V powder was dry blended with elemental Fe at 1, 3, and 5 wt.%, and the powder blends were processed using a TRUMPF TruPrint 1000 system under an argon atmosphere. The investigated processing window corresponded to a volumetric energy density (VED) range of about 38.6–87.7 J/mm³. Processability was assessed using Archimedes density measurements, X-ray computed tomography (XCT), image analysis, and surface roughness measurements. Microstructural and phase evolution were examined by optical microscopy (OM), scanning electron microscopy (SEM), and X-ray diffraction (XRD), while local mechanical behavior was evaluated by nanoindentation. The results showed that adding Fe did not have a negative effect on densification within the studied processing range. The relative density remained above 99.4% for all conditions, and the defect analysis showed only a very small amount of mostly isolated porosity. No severe keyhole defects or continuous tunnel-like defects were observed. H³/Eᵣ² ratios. Overall, in situ Fe alloying appears to be an effective way to tailor L-PBF Ti-6Al-4V, especially at 3 wt.% Fe, where high densification, grain refinement, β stabilization, and reduced elastic modulus are achieved together.