TO THE ISSUE OF THE ULTIMATE PURIFICATION OF METALS

The paper considers issues related to the ultimate content of impurity elements in metals in the processes of their refining by evaporation and distillation in vacuum, zone recrystallization and electromigration. It is shown that at all refining methods, with an increase in the number of refining cycles and the duration of the process, a “saturation effect” arises, associated with the achievement of the ultimate concentrations of impurity elements in refined metals. The reasons for the impossibility to produce absolutely pure metals have been discussed.