KCl-NaCl equilibrium phase diagram. Phases at equilibrium for the chemical system KCl-NaCl are shown as a function of chemical composition (mole percent NaCl) and temperature at atmospheric pressure (1 bar). This chloride system is similar to the alkali feldspar system in that there is complete solid solution between the KCl and NaCl phases at elevated temperatures. End member compositions melt at higher temperatures than intermediate compositions. The liquidus has an azeotrope minimum at 58 mole percent NaCl. At lower temperatures there is a two-phase region bounded by a solvus. This diagram is based on the collection of alkali halide phase diagrams by Sangster and Pelton (1987).
Mole % NaCl:
Temperature:
