[en] A projection of solidus surface is plotted for the partial Ru-ZrRu-ZrIr-I) system. It is shown that ternary compounds are not formed in this system. Isostrucutural ZeRu and ZrIr phases form a continuous series of solid solutions. A high reciprocal solubility of ruthenium and iridium is observed both in primary solid solutions and in intermediate ZrRu₂, ZpIr₂ and ZrIr₃ phase (from 0.29 to 0.5%). Four triphase fields exist at subsolidus temperatures: < Ir > + < Ru > + < ZrIr₃ >, < ZrIr₃ > + < ZrIr₂ > + < ZrRu₂ >, < ZrIr₂ > + < ZrRu₂ > + Zr(Ru, Ir) and < Ru > + < ZrIr₃ > + < ZrRu₂ > as well as nine duel phases corresponding to them. Temperatures of the melting start for the Ru-ZrRu-ZrIA-Ir system alloys decrease to the Zr-Ru side of the concentration triangle