In-situ solidification and metallic flow visualizations with X-rays
Manufacturers of high performance metallic alloys and electronic crystals need to understand solidification from alloyed melts in order to improve processes. Predictive liquid metal modelling was considered necessary to improve material quality. The international microgravity programs heightened awareness of the impact the fluid flow in the melt has during solidification processing on properties of the solid. Numerical codes were developed for most processing systems. Validation was done by comparative benchmark problem solving and experiments with transparent model melts, without completely understanding its appropriateness. For a long time research on liquid metal fluid dynamics has been hampered by lack of flow and density visualization in the melt phase.
This presentation describes a radioscopic flow visualization technique. It will be shown that real-time liquid metal flow visualization and in-situ observation during solidification/ melting processing are very powerful and deliver results that need to be clarified. These include gravitational segregation in the melt, actual dissolution state of the melt above liquidus, a threshold in natural convective flow, and double diffusive flow patterns. So far, many experiments challenge some of the conjectures made in numerical simulations.