On the criteria for the surface activity and classification of the surface tension isotherms from the data on the melt structure

The existence has been considered of the interrelation between structures of metal melts of eutectic systems and systems having negative heat of mixing with participation of p-elements and their physicochemical properties. It has been shown that the appearance of extremums in experimental isotherms of density and surface tension is caused by the change of the nature of the atomic ordering in the melt. The structure elements forming in the melt may exhibit a surface activity if the binding energy between atoms constituting this structural element is higher than their energy of binding with the basic metal–solvent. It has been found that in this case the criterion for the surface activity in the systems having any type of the interaction may be the appearance of a covalent component in the structure of the chemical bond between atoms of the melt of the same kind as well as the presence of the decompression regions.