Experimental investigation of the pressure of saturated vapors of liquid alloys of alkali metals at high temperatures: $\mathrm{Na}$–$\mathrm{K}$ system

The saturated vapor pressure of liquid sodium–potassium alloys of five compositions ($33.5$, $50.0$, $66.6$, $68.0$, and $80.0$ at.$\%$ K) is investigated in the temperature range from $758$ to $1297$ K by a method using the $U$-tube pressure gage method. The alloys are prepared by the gravimetric method, and the determination error of their composition is $\pm0.1$ wt $\%$. The purity of the starting sodium and potassium is fairly high, and the total content of metallic and gaseous impurities in each of them does not exceed $1\times10^{-2}$ wt $\%$. The confidence experimental error in the investigated temperature range is $1$–$2\%$, with its higher value relating to lower temperatures. The measurement results are statistically processed to derive approximating equations for the pressure of saturated vapors for all of the investigated alloys. The pattern of the concentration and temperature dependence of the deviation of the experimental data from Raoult's law is analyzed.