Unveiling the Effects of Processing Parameters on Microstructure, Mechanical Properties, and Corrosion Resistance of High-Nb TiAl Alloy Fabricated by Laser Powder Bed Fusion

This study elucidates the impact of laser volumetric energy density (VED) on the densification behavior, microstructural evolution, wear resistance, and corrosion resistance of high-Nb TiAl alloys fabricated via laser powder bed fusion (LPBF). Experimental characterization results showed that relative density first increased and then decreased with increasing VED, reaching a maximum density of 97.13% at 66.67 J/mm3. Across the process windows, the high-Nb TiAl alloys were primarily composed of γ-TiAl, α2-Ti3Al, and β/B2 phases with varied proportions. Mechanical property analysis showed that the alloy attained a maximum average hardness of 422 HV0.5 at 81.48 J/mm3, due to the accumulation of harder α2 and B2 phases. However, the high-Nb TiAl alloys fabricated at 66.67 J/mm3 exhibited excellent wear resistance, as evidenced by wear track widths and depths of 971.71 μm and 21.83 μm, respectively. Abrasive and oxidative wear were identified as the primary mechanisms. Meanwhile, this specimen also exhibited excellent corrosion resistance, a corrosion current density of 1.421 × 10−6 A/cm2, attributed to the coupled dense passive film of TiO2 and Al2O3 that prevented chloride ingress. The findings in this work may provide a critical experimental reference and theoretical underpinnings for LPBF-fabricated lightweight structural materials.