X-Ray and Neutron Radiographic Experiments on Particle-Laden Molten Metal Flows

In metallurgical processing, non-metallic inclusions contaminating metallic materials are one highly relevant challenge. Bubble injection into molten metals boosts the inclusion control and removal, thus enhancing metal homogenisation and purification. Although this principle of bubble flotation has been used for a long time, the effects of bubble–inclusion interactions in molten metals are not yet well researched. Imaging measurements of multiphase metal flows are challenging for two main reasons: the metals’ high melting temperatures and their opaqueness for visible light. This work focuses on X-ray and neutron radiographic experiments employing low-melting gallium alloys laden with model particles smaller than 1 mm in diameter. Both, bubbles and particles, are visualised simultaneously with high spatial and temporal resolution in order to analyse their motions by tracking algorithms. We demonstrate the capability of time-resolved X-ray and neutron radiography to image multiphase flows in particle-laden and optically opaque liquid metals, thus contributing to pave the way for systematic investigations on bubble–inclusion interactions in molten metals.