An Investigation into Solidification of Hypereutectic Al-Si Alloys

Prof A.L. Greer (University of Cambridge), external examiner (in his report): This research project has dealt with the solidification of hypereutectic Al-Si alloys, a topic of continuing practical importance. The candidate gives adequate reviews of the theory of crystal nucleation in melts and of prior work on hypereutectic Al-Si alloys. The experimental work has involved casting, heat treatment, X-ray diffraction, metallography, differential thermal analysis and electron back-scatter diffraction. It appears that all of the techniques used have been standard, but the work has been competently carried out. The heart of the work is examination of the effects of phosphorous and strontium additions on the number of primary silicon particles per unit volume. The results have been fitted to a nucleation model by Perepezko. The nucleation temperature has been identified as a key variable. Prof I. Todd (University of Sheffield, UK), the supervision team: Masoumeh's research at the time focused on the simultaneous modification of both primary and eutectic silicon in aluminium silicon casting alloys, a topic that remains challenging and has significant commercial and technological value.