Characterization of Sintered Ti-6Al-4V Powders in Electron Beam Additive Manufacturing

In the powder-based electron beam additive manufacturing (EBAM) process, preheating is applied, prior to the melting stage, to aggregate precursor powders and to reduce the residual stresses in the build parts. Preheating results in sintering of the powders, which serve as the initial work material for the subsequent melting stage. In this study, sintered Ti-6Al-4V alloy powders from preheating were obtained and studied. The specimens of sintered powders, also processed to prepare metallographic samples, were observed and characterized by optical microscopy (OM) and scanning electron microscopy (SEM). The results show that after preheating, some powders are partially “melted” and necks between adjacent particles are formed with metallurgical bonds. The sintering evidence, necking, can be noted on both the build plane and the side surface (normal to the build plane). The Baktetwave α-β structure is identified in the powders, while the martensitic structure is formed in the solid EBAM part.