METAL CHEMISTRY OF SCANDIUM IN BINARY SYSTEMS FORMED WITH PLATINUM-GROUP METALS AS THE BASIS FOR CONSTRUCTION MULTICOMPONENT SYSTEMS BASED ON THOSE METALS

摘要

Major trends are considered in the physicochemical interaction in binary systems formed by scandium with the platinum metals (ruthenium, rhodium, palladium, osmium, iridium, and platinum) from the characteristic features of the phase diagrams and the use of metal-chemical factors governing the formation of intermetallides with various stoichiometry and structure types in those systems (the size, electron-concentration and electronegativity factors). The values for those factors have been established that are favorable to the formation of phases with Sc:Pt' stoichiometry (Pt' is a platinum metal), namely: 1:3 (structure type AuCu_3, 1:1 (CsCl type), 11:4 (Zr_(11)Os_4 type), and 44:7 (Mg_(44)Rh_7 type). Published data and the authors' own evidence on the structure of bounding binary systems have been used with evidence on the physicochemical interactions in the Sc - Ru - Rh system in forecasting the type of phase Equilibria occurring in systems of Sc- Pt' - Pt'' type (Where Pt', Pt'' = Ru, Rh, Pd, Ir).