| Abstract Scope |
The complex solidification and fluid flow phenomena during additive manufacturing (AM) of metals, polymers, glass, and composites are not well understood due to their occurrence at extremely short spatiotemporal scales — micrometres and sub-milliseconds. Here, we will report the applications of synchrotron X-ray imaging combined with advanced sensing and imaging process technologies to gain insights into these phenomena during AM. We will present and explain the evolution of melt pool, vapour depression/keyhole, and defects, e.g. porosity, cracks, and spatters, during AM. Our results show that alloys and their composites undergo rapid heating, melting, vaporisation, solidification, and phase transformations. However, polymeric and glass powders undergo melting, viscous merging, volume expansion, warping, solidification, and shrinkage before forming solid tracks. Lastly, we also uncover a range of bubble formation and evolution mechanisms in these materials, which are then used to verify and validate high-fidelity process simulation of AM processes. |