Experimental analysis shows volumetric energy density affects hardness and tensile strength in Ti-22Al-25Nb alloy, suggesting optimal parameters are crucial.
In this study, the Ti-22Al-25Nb alloy was successfully fabricated using the microlaser powder bed fusion (μ-LPBF) process. A systematic investigation was conducted on the influence of volumetric energy density (VED) on its microstructure and mechanical properties. The results demonstrated that VED played a critical role in regulating the relative density by adjusting the laser power (30 - 40 W), scanning speed (800 - 900 mm/s), and scanning interval (40 - 45 μm). Both excessively low and high VED levels led to density fluctuations, primarily due to unmelted powder or the formation of pores. Regarding mechanical properties, tensile strength and hardness exhibited an initial increase followed by stabilization as VED increased. Under optimal processing parameters (VED = 109.38 J/mm 3 ), the tensile strength of Sample 2 reached 1,052.15 MPa, with a Vickers hardness of 320.4 HV. Fracture analysis revealed a reduction in unmelted powder content in samples processed at higher VED levels, accompanied by an increase in dimple quantity and uniform distribution, which indicated enhanced ductility. This study confirmed that the ultra-high cooling rate inherent to μ-LPBF can effectively refine grains; however, optimization of VED and process parameters is essential for achieving balanced densification and defect control. These findings provide valuable guidance for the additive manufacturing of high-precision Ti-22Al-25Nb components in aerospace applications.
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Li et al. (2025) studied this question.