The solidndash;liquid phase diagrams were investigated to 60 kbar for elemental sodium, potassium, and various sodiumndash;potassium alloys. The data for Na and K are in general agreement with those of earlier workers. In the alloy system the temperatures of both the peritectic and eutectic halts increase as the pressure increases, but with different slopes, so that the two invariant points merge at approximately 35 kbar. Above this pressure, two halts are again observed. One increases with increasing pressure, and the other decreases with increasing pressure up to 55 kbar, where it abruptly starts increasing again. Melting points for samples in the 0.6ndash;0.8 mole fraction potassium range indicate that an NaK2intermetallic compound may form at high pressures.
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