Application of synchrotron X-ray imaging to the study of directional solidification of aluminium-based alloys
Résumé
Third generation synchrotron X-ray sources like ESRF (European Synchrotron Radiation Facility) have enhanced the capabilities of in situ and real-time X-ray imaging so that it is possible to follow the solid–liquid interface dynamics on metallic alloys with improved spatial and time resolution. In this paper, we focus on the solidification patterns of Al based alloys, visualised by absorption and phase contrast radiography at ESRF. Two metallic systems were selected for this study: (i) Al–3.5 wt% Ni (with and without refiners) for the analysis of columnar growth and equiaxed growth, and the influence of the refiners on the columnar to equiaxed transition (CET), which is a key point in solidification processing, (ii) Al72.4Pd20.5Mn7.1 for the analysis of interface shape of growing quasicrystals (QCs). For both alloys, striking features were observed and a preliminary discussion is presented. Those results demonstrate the high potential of ESRF Synchrotron source for the characterisation of the dynamical formation of the solid microstructure in materials processing.