Calculating the thermodynamic parameters of the surface layer of the binary sodium-potassium system

The composition and number of surface monoatomic potassium layers in Na-K alloys are calculated on the basis of theory of the thermodynamic stability of surface layers of metal alloys with respect to their thickness. The surface layer of Na-K alloys is shown to be thermodynamically stable at surface layer thickness of two monoatomic potassium layers in the range of compositions with K in Na content of ∼13–15 at %. Good agreement is obtained using the surface activities of the components in binary metal melts as criteria.