Diffuse reflectance spectroscopy for the qualification of powder blends for additive manufacturing

Additive manufacturing (AM) offers significant opportunities for alloy development through direct manufacturing from powder blends. The quality of the AM process is heavily influenced by the properties of the powders used, particularly their homogeneity and flowability. This study evaluates two Al5xxx series powder blends with ZrB2, CaB6, and Ta additives for morphology, flowability, rheology, and diffuse reflectance. While flowability and rheological metrics, such as those derived from rotating drum and FT4 tests, showed variability across different blends, their correlations were limited by base powder morphology differences. In contrast, diffuse reflectance spectroscopy (DRS) reliably detected additive type and weight ratios with a normalized difference of only 2.4 % between Al5052-additive and Al5254-additive blends, despite their distinct morphologies. This highlights DRS as a non-destructive tool for quality control in powder blend homogeneity. Furthermore, its potential for in situ monitoring in PBF machines could provide real-time blend uniformity data, enabling layer defect detection.