Microstructure formation in centrifugally cast Al-Bi alloys

A numerical model describing the microstructure evolution in a centrifugally cast alloy with a miscibility gap in the liquid state is developed. Centrifugal casting experiments were carried out with Al-Bi alloy. The microstructure formation in the centrifugally cast Al-Bi tube was calculated. The calculations demonstrate that generally the moving velocity of the minority phase droplets due to the centrifugal force is much larger compared to the Marangoni migration velocity of the droplets during the liquid-liquid phase transformation. Thus, a layer rich in Bi particles forms on the outside surface and a region poor in Bi particles forms on the inner surface of the centrifugally cast Al-Bi tube. The numerical results show a good agreement with the experimental ones. (C) 2010 Elsevier B.V. All rights reserved.