In Situ Investigation of Dendrite Deformation During Upward Solidification of Al-7wt.%Si

International audienceThe in situ investigation of dendrite deformation during solidification processing is an ongoing challenge because of the technical difficulties in carrying out experimental observations and direct measurements in metallic systems that are opaque to visible light and have a high melting temperature. Over the last 20 years, x-ray imaging has been established as a method of choice to overcome this experimental barrier by taking advantage of the increased capabilities of third-generation synchrotron x-ray sources, providing information on growth process and semisolid deformation that is not available otherwise. In this article, we present results showing that the unique combination of synchrotron x-ray radiography and synchrotron white beam x-ray topography can help to reveal the deformations that dendritic microstructures undergo during the upward directional solidification of Al-7wt.%Si alloys. Particular focus will be placed on the bending phenomena of dendrites because of gravity, which may precede fragmentation in the case of well-developed secondary arms