Abstract
In electron beam melting (EBM) metal 3D printing, accurate characterization of metal particles is important for efficient layering and understanding the potential for reuse of milled particles after processing. Factors such as “flowability” and “oxygen content” of metal particles affect particle properties such as shape, sphericity, particle size distribution, specific surface area, true density, and porosity. Currently, however, the combined evaluation of these factors is insufficient and lacks clear criteria for determining the reusability of metallic particles.
Therefore, the purpose of this study was to understand the morphology and determine the reusability of Ti-6Al-4V (Ti64) metal particles by evaluating their particle characteristics. Ti64 alloy particles produced by gas atomization were evaluated as virgin particles. In addition, metallic particles produced by simple spatula grinding of the sintered compact obtained as a byproduct of molding by EBM metal 3D printing at 700 ºC and 800 ºC were used as recycled particles for comparative evaluation.
As a result, particle shape could be evaluated by SEM images and dynamic image analysis, and it was found that some of the recycled particles were slightly increased due to sintering of satellite particles, but most of the recycled particles were not significantly different from virgin particles in terms of particle size, shape, and particle size distribution. By evaluating these results together with specific surface area and porosity using the Kr gas adsorption isotherm and He gas displacement method, similar results that can be interpolated were obtained, and the morphology of each Ti64 alloy was understood, providing insight into the possibility of recycling milled particles.
