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SUMMARY:In situ synchrotron X-ray characterisation of microstructure forma
 tion during solidification of Al-based alloys - Dr. Guillaume Reinhart\, I
 nstitute Materiaux Microélectronique Nanosciences de Provence\, Marseille
DTSTART:20110218T110000Z
DTEND:20110218T120000Z
UID:TALK29569@talks.cam.ac.uk
CONTACT:Dr Sandra Korte
DESCRIPTION:The primary microstructure formed during the solidification st
 ep has a major influence on the properties of materials processed by major
  techniques (casting\, welding…). In situ and real-time characterisation
  by synchrotron X-ray imaging is the method of choice to unveil the dynami
 cal formation of the solidification microstructure in metallic alloys\, an
 d thus provide precise data for the validation of the theoretical predicti
 ons that is needed for advancement of modelling and numerical simulation. 
 After a description of the experimental procedure used at the European Syn
 chrotron Radiation Facility (ESRF)\, dynamical features occurring during t
 he formation of the columnar and equiaxed grain structure in Al-based allo
 ys are presented. Convective flows initiated by residual transverse temper
 ature gradients are amplified by the solute rejection during the solidific
 ation process. Beyond fluid flow interaction\, earth gravity induces stres
 ses\, deformation and fragmentation in the dendritic mush. Settling of den
 drite arms and equiaxed grains thus occurs\, in particular in the columnar
  to equiaxed transition (CET). Quantitative analysis of the grey level in 
 radiographs enables the analysis of solute segregation\, which noticeably 
 results in solutal poisoning of growth when equiaxed grains are interactin
 g. Finally\, the extension of such investigation to the study of materials
  with a high melting point such as superalloys will be discussed. \n
LOCATION:Department of Materials Science\, Gordon Seminar Room
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