Secondary Supercooling in Binary Eutectic Alloy Systems

Abstract

In two previous communications the authors reported on the primary supercooling results obtained for bulk samples of several binary eutectic alloys. It was shown that primary supercooling, when determined from the arrest or reversal point on a continuous cooling curve, is dependent upon the cooling rate and the alloy composition The nucleation and growth of the secondary phase, i.e. the onset of eutectic solidification, also requires supercooling, the amount of (secondary) supercooling depending on the primary phase present. This paper reports on the secondary supercooling results obtained for bulk samples of alloys from several binary eutectic systems, and compares these with supercooling results reported for liquid droplets of the same alloys. An apparent relationship between the extent of secondary supercooling and the magnitude of the distribution coefficient is noted and discussed briefly.