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Published online by Cambridge University Press: 21 February 2011
A novel technique was used to measure directly the interface temperature and growth rate during solidification of pure gallium. The technique utilizes the Seebeck emf generated across two solid-liquid interfaces to determine the interface supercooling and an optical microscope to measure the solidification rates. The growth rate measurements were made in the range of about 0.08 to 1400 μm/s for 1.59 to 3.6°C interface supercoolings (ΔT) on the (111) interface of high purity gallium in glass capillaries. A plot of logv vs. 1/T for dislocation-free interfaces followed two straight lines, one for higher than about 1 μm/s growth rates and the other for the lower rates. The data at the lower rates correspond to the lateral growth mechanism for which a single nucleus forms and spreads across the interface before formation of the next nucleus, while those at the higher solidification rates correspond to the lateral growth by the multi-nucleation and spreading mechanism.
