ALLOY BEHAVIOR AND THE SC-RU-RH PHASE-DIAGRAM .1. SOLIDUS SURFACE IN THE RU-SCRU-SCRH-RH PARTIAL SYSTEM

Data obtained by microstructural, x-ray phase, and microprobe analysis have been used together with measurements of the temperature for the start of melting by the Pirani-Alterthum method to obtain a projection of the solidus surface in the partial Ru-ScRu-ScRh-Rh system on the c oncentration triangle. It is found that ternary compounds are not form ed. The solidus surface is made up of five surfaces for the primary cr ystallization of solid solutions bared on ruthenium and rhodium togeth er with phases based on the compounds ScRu2, ScRh3, and the delta phas e (a continuous series of solid solutions between isostructural phases of CsCl type based on ScRu and ScRh), together with seven lineated su rfaces, which enclose two-phase volumes, and three isothermal areas, w hich relate to nonvariant four-phase equilibria involving the liquid: L reversible arrow [Ru] + [ScRu2] + delta (1650 degrees C), L + [Rh] r eversible arrow [Ru] + [ScRh3] (1640 degrees C) and L reversible arrow [Ru] + delta [ScRh3] (1520 degrees C).