Anomalous Nucleation in Undercooled Melts Processed by Electromagnetic Levitation

Recent experiments using electromagnetic levitation in reduced gravity have confirmed prior observations of anomalous nucleation of the solid in undercooled melts under specific conditions. All indications are that this effect is dynamical, not chemical: the same sample undercools over 300 °C before and after the anomalous event, but maintains the liquid state for only a few seconds when held at a more modest undercooling in the range of 0–50 °C. The new experimental results and related modeling will be examined in comparison to the hypothesis that the solidification is triggered by cavitation in the melt. This platform may provide data relevant to a better quantitative understanding of the effect of ultrasonic processing on grain refinement of terrestrial castings.