Stability of Solid Phases in the Ternary Systems of Silicon and Carbon with Rhenium and the Six Platinum Metals

Abstract

Possible reactions in the ternary systems of carbon and silicon with rhenium, ruthenium, rhodium, osmium, and iridium have been studied at 1600°, 1340°, 1170°, 1350°, and 1340°C, respectively. At these temperatures the only stable phases are solid metal silicides and silicon carbide. Approximate ternary diagrams are fixed for the systems carbon‐silicon‐palladium and carbon‐silicon‐platinum by examination of phases formed during cooling from above the liquidus temperatures. Lower limits to the thermodynamic stability of many of the metal silicides are set by the stability of these phases relative to reaction with carbon to form silicon carbide. Higher limits to the stability of the other metal silicides are set by their instability relative to reaction with carbon to form silicon carbide. These limits are used to estimate heats of formation for the platinum‐family metal silicides. Measured and estimated heats of formation of other transition metal silicides are tabulated.