Metallurgical variations of Ti-6Al-4 V powder particles after reuse in powder bed fusion –electron beam melting processes

Powder Bed Fusion (PBF) is part of the category of additive manufacturing processes and includes Electron Beam Melting (EBM). Metal powder that has previously been atomized is the raw material used in all EBM processes. Reusing surplus powder after its production cycle lowers manufacturing costs and improves productivity. Depending on how many times it has been reused, recycled powder may vary from virgin starting powder in several aspects. Additionally, parts produced through electron beam melting may have lower mechanical strength due to deterioration of the powder quality. The goal of this work is to examine the morphology, defects, and microstructure of three batches of Ti-6Al-4 V powders: one batch of virgin powder that was produced via plasma atomization, called Batch C, one batch that was reused five times, called Batch B, and one batch that was reused 100 times, called Batch A. The results demonstrated that although the virgin powder had a large number of satellites, its shape was almost perfectly smooth and spherical. On the other hand, there were fewer satellites, more morphological deterioration, and additional defects in the two recycled powders. The rapid cooling that occurs during the atomization processes leads to the martensitic α' phase, which is responsible for the microstructure found in the virgin powder; in contrast, the microstructure was shown to be coarsened in both recycled powders.