A series of compositions across the niobium-rhodium- silicon ternary diagram from Nb₃Rh to 75 atomic percent niobium-25 percent silicon, were prepared by arc-melting compacts of high-purity powders. Both x-ray diffractometer and camera techniques were used to analyze the resulting structures.

No measurable amount of silicon was found to substitute for rhodium in the Nb₃Rh structure. The 75 percent niobium-25 atomic percent silicon composition contains niobium plus an unidentified phase assumed to be Nb₅Si₃. The Nb-Rh sigma phase extends into the ternary system to at least 10 atomic percent silicon. All ternary alloys investigated contained three phases. These phases were one or more unidentified phases combined with either A₃B or sigma or both.