Surface modification of Ti-6Al-4V powder during recycling in EBM process

Electron beam melting is an additive manufacturing technology in vacuum that suits Ti-6Al-4V parts, which has a high affinity with oxygen. Since the high cost of the feedstock powder, the un-melted powder is often recycled in the subsequent process. In this study, the influence of powder reuse on the surface characteristics of Ti-6Al-4V powder is examined using a variety of technology including scanning electron microscopy, X-ray photoelectron spectroscopy, and Auger electron spectroscopy. The modification of surface morphology and chemistry either generally or locally are revealed and discussed, which helps the creation of powder recycling strategy. Compared with fresh virgin powder, worn and rougher powder particles are observed after recycling. Meanwhile, the average oxide thickness is slightly increased, and less Al enrichment was found at the surface. Locally varied chemistry/oxide thickness on different powder particles or different location on the same particle is observed.