Thermophysical properties of [(0.54NaF – 0.46AlF3)eut - (0.55KF – 0.45AlF3)eut]-quasi-binary system

The solidus and liquidus temperatures and fusion heat were investigated in [(0.54NaF–0.46AlF3)eut-(0.55KF–0.45AlF3)eut]-quasi-binary system. Two maximum liquidus temperatures (~ 1000 K) were observed at KF/(KF + NaF) ratio equal to 0.15 and 0.65. The minimum liquidus temperature (~ 900 K) was observed at KF/(KF + NaF) ratio equal to 0.3. The solidus temperatures were related to complex compounds KAlF4 and K2NaAl3F12. The heat of fusion of eutectic compositions was found to be directly proportional to melting point. Thermal diffusivity of two eutectic mixtures was studied by laser flash method in temperature interval 300–800 K. Thermal conductivity was calculated using density and heat capacity data obtained for the same mixtures. Both thermal diffusivity and thermal conductivity are reduced with temperature for samples investigated. Thermal conductivity of potassium eutectic changes from 2.3 at 300 K to 1.8 W∙m−1∙K−1 773 K, and that of sodium eutectic reduces from 1.65 W∙m−1∙K−1 at 300 K to1.45 W∙m−1∙K−1 at 773 K.