Morphology and orientation of growing dendrites in GaIn alloy characterized by synchrotron X-ray techniques

The dendrite growth kinetics and morphology have been of great interest in the solidification science and casting industry. A detailed analysis of the particular solidification phenomena requires techniques with a better spatial and temporal resolution. High resolution experimental data are also very important for verification of the existing microstructural models. We demonstrate an advantage of the synchrotron X-ray sources, which allows the unique combination of in situ synchrotron X-ray radiography with a spatial resolution of less than 0.5 µm and synchrotron X-ray diffraction. The directional solidification experiments of Ga–25wt%In alloys were performed at the ROBL beam line (BM20, European Synchrotron Radiation Facility, Grenoble) at an energy of 28.5 keV. The study is especially focused on the sidearm evolution, refraction and detachment, dendrite morphology and orientation. Typical radiographs of sidearm evolution of an indium dendrite are shown in Fig. 1. The development of sidearms is quantified by an image analysis in a manner appropriated for comparison to simulations. Furthermore, we report on first attempt of reconstruction of crystallographic orientation of growing dendrites by using the CaRIne crystallography software.