Gravitational Influence on Eutectic Solidification

The study of gravitational effects on solidification has been encouraged in part by the opportunities to conduct research in the low gravity environment of a laboratory orbiting earth. On the other hand, centrifuges have been applied to solidifying alloys to elucidate the role of elevated gravity in determining phase equilibria and controlling macrosegregation. Research on eutectic alloy solidification under extremely high centrifugal fields > 100 000 g has uncovered a wealth of new evidence demonstrating the significance of both free and convective flows in determining the extent of phase segregation. The importance of nucleation behavior is addressed, and a mechanism for the strong phase separation seen in alloys solidified in centrifugal fields is postulated on the basis of cloud formation models in atmospheric convection. \Sn sub 61.9 Pb sub 38.1 is discussed.\