Аннотация:Peculiarities in structure of phase diagrams of ternary systems containing ferromagnetic metals (Fe, Co and Ni) and refractory transition metals of V group of the Periodic system (Nb and Ta) have been established by methods of physicochemical analysis. Phase equilibria in studied systems are determined by interaction of solid solutions on the base of intermetallides with close packing of atoms. It permits to distinguish the features typical for given systems. So, interaction of β-phases isostructural to Fe 7W 6 compound, in all cases leads to formation of ternary solid solutions. An attempt has been undertaken to assess the concentration stability of topologecally close packed phases of other types with the help of estimation of change in factor of electronic concentration.