In situ analysis of equiaxed growth of aluminium-nickel alloys by x-ray radiography at ESRF

We present results obtained at the ID19 beamline of the European Synchrotron Radiation Facility (ESRF) by synchrotron x-ray radiography during the solidification of Al-Ni alloys. We focus on columnar dendritic and equiaxed solidification, and the transition between the two regimes. The columnar to equiaxed transition is a critical and still pending issue in metallurgy. By making use of the high potential of synchrotron experimental tools for in situ and real-time characterization of the solid-liquid interface during directional solidification, we were able to provide insight into key physical phenomena, in particular, sedimentation, interaction and arrangement of equiaxed grains.