Directional solidification of rod eutectics in $NaNO_3$-NaCl system

The partial phase diagram of $NaNO_3$-NaCl system was investigated and the eutectic temperature was determined as $294.5^{\circ}C$. A typical rod eutectics of $NaNO_3$-4.56 wt%NaCl was directionally solidified. The results of interrod spacing, ${\lambda}_E$ as a function of growth velocity, V, were. obtained as ${\lambda}_E\;V^{0.39}\;=\;5.26$ (temperature gradient, $G_l\;=\;21.4^{\circ}C/mm$) and ${\lambda}_E\;V^{0.32}\;=\;5.45$ ($G_l\;=\;3.9^{\circ}C/mm$) and the exponent numbers of growth velocity were smaller than the theoretical value, 1/2. The sample rotation applied during directional solidification made the interrod spacing decrease slightly.