  Thermodynamic equilibrium can be sometimes reached at the interaction between
metal and oxide melts in high temperature welding and metallurgical processes.
Calculation of equilibrium phase composition is also one of the stages (along
with kinetics analysis) of building an end-to-end physical and chemical model
of real processes. Developing a thermodynamic model of high temperature
processes is described in many scientific sources (1-18). Thermodynamic
patterns of oxidation-reduction reactions on the metal-slag melt interface are
also taken into account when building phenomenological models of real welding,
facing, and metallurgical processes (19-30). This paper deals with calculating
an equilibrium phase composition for a specific reaction. A method proposed
herein also takes into account an interaction among any number of chemical
reactions in the metal-oxide melt interface that form an equilibrium phase
composition
