EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Given nearly ambient temperature conditions in laser powder bed fusion (LPBF), spatter accumulation is usually the main source of powder degradation. Spatter particles are normally molten/partially molten or overheated particles ejected from the melt pool and its vicinity, that are oxidized due to the presence of residual oxygen in the build chamber. Melt pool ejections are finer and have a higher temperature and hence get highly oxidized during the solidification and cooling process. In this study, spatter generated during the LPBF fabrication of Ti-6Al-4V parts under different atmospheric gas conditions (including Argon, Helium, and a mixture of both) were analyzed. Bulk oxygen analysis has shown a slight decrease in oxygen content of spatter particles with the introduction of He gas, and the decrease was highest in 100% He environment. Morphology analysis of these spatter particles by scanning electron microscopy (SEM) showed that the surface was covered with oxide particulates enriched in Al oxide alongside Ti-based oxides. Further surface analysis by X-ray photoelectron spectroscopy (XPS) confirmed the presence of Al- and Ti-based oxides. The depth profile analysis by XPS illustrated a decrease in oxide layer thickness with the introduction of He gas, in agreement with the trend in bulk oxygen content. The results indicate that introducing He as a processing atmosphere is a potential solution to increase both, productivity and powder reusability.