Powder sintering kinetics during electron beam based additive manufacturing

Electron Beam Powder Bed Fusion (PBF-EB) allows not only for the additive manufacturing of fully dense metallic components via melting but also parts with defined local pore structures and tailored functional properties through selective sintering. The hybrid PBF-EB technology based on the combination of selective sintering and melting is, e.g., of great interest for the fabrication of porous electrodes composed of titaniumbased alloys with high specific surface area, which are widely used for electrochemical processes (e.g., as anode for water electrolysis cells). This study aims to provide a comprehensive understanding of the sintering kinetics of Ti6Al4V (especially in the first and second sintering stages) during PBF-EB. The sintering degrees of the PBF-EB-processed Ti6Al4V samples are characterized by determining the thermal diffusivity measured by laser flash analysis. At the same time, the thermal history during PBF-EB is analyzed using a pyrometer. The correlation between the sintering degrees and the process parameters utilized in the PBF-EB procedure is discussed by calculating the activation energy of sintering and described using a master sintering curve. Based on the findings of this study, it is possible to control the sintering process of Ti6Al4V powder in a targeted manner by utilizing various PBF-EB parameters.