Phase equilibria in the system Al-Rh

Methods of differential thermal analysis, x-ray diffraction, microstructural analysis and electron probe microanalysis are used to study alloys of the Al-Rh system over the whole concentration range. It is established that the phase of equiatomic composition AlRh melts congruently at 2060°C and it has an extended range of homogeneity (45.1–54.2 at.% Rh). The solubility of aluminum in rhodium reaches 9 at.%, decreasing to 6 at.% at 850°C. Coordinates are determined for the eutectic point l ⇆ AlRh + 〈Rh〉 as 70 at.% Rh and 1715°C. The existence of intermediate phases, their crystal structure, and also the method of forming phases in the field of composition rich in aluminum given in publications are confirmed. __________ Translated from Poroshkovaya Metallurgiya, Nos. 5–6(449), pp. 48–56, May–June, 2006.     

Alloy structures and phase equilibrium diagram of the Hf-Ru-Ir system III. Solidus surface and 1350°C isothermal section of the state diagram in the Hf-HfRu-HfIr region

Translated from Poroshkovaya Metallurgiya, No. 3, pp. 61–67, March, 1992.     

Physicochemical Investigation of the Reaction of Components of the Si — Al — O — N — Ti System in the Si3N4 — Al2O3 — AlN — SiO2 — TiN — TiO2 Region. Part 2. Subsystems Si3N4 — AlN,TiN — AlN,Al2O3 — AlN

The reaction of components of the Si — Al — O — N — Ti system in its elements Si ₃N₄ — AlN, TiN — AlN, and Al ₂O ₃ — AlN was investigated by differential thermal and x-ray diffraction analysis. It was established that upon hot pressing mixtures of Si₃N ₄ and AlN (up to 1950°C) free silicon is formed by the decomposition of Si ₃N₄, which reacts with oxygen present as an impurity to form SiO. When TiN reacts with AlN a phase with the spinel structure (Al₂₃O ₂₇N ₅), which can form only in the presence of excess oxygen, appears in addition to the initial components. Spinel is also produced by the reaction of Al ₂O₃ with AlN. In this case a eutectic between Al ₂₃O₂₇N₅ and Al₂O₃ is observed.     

Phase Equilibria in the Mg – Al – Ca System (Region 50-100 mass% Mg)

Phase equilibria in the ternary system Mg – Al – Ca in the composition range 50-100 mass% Mg were studied by the methods of differential thermal, xray diffraction, electron-probe and microscopic analysis. The projection of the liquidus surface on the concentration triangle, isothermal section at 150°C and polythermal sections at 4.5, 8.5, and 16 mass% Al were constructed. It was determined that additions of Al and Ca decrease the liquidus temperature of magnesium alloys (from 650 to 438°C). It is shown that the three-phase region + 2Ca> + 17Al₁₂> exists at 150°C with the corresponding two-phase fields. The temperature dependence of the homogeneity range of the Mgbased solid solution was determined, and also the temperatures of the phase transformations which occur in the investigated range of compositions in the system.     

Alloy composition and equilibrium phase diagram for the Sc–Ru–Rh system. V. 930°C isothermal section of the Sc–ScRu–ScRh partial system

Microstructure, x-ray diffraction, and electron-microprobe methods have been applied to study an isothermal section at 930°C of the Sc–ScRu–ScRh partial system. As no ternary compounds are formed in the system, the phase equilibria involve intermediate phases based on binary compounds that exist in the bounding Sc–Ru and Sc–Rh systems: Sc₅Ru₃, Sc₂Ru, Sc₁₁Ru₄, Sc₄₄Ru₇, Sc₃Rh, and the δ and η phases (continuous series of solid solutions between the isostructural phases, respectively, ScRu and ScRh (with the CsCl structure type), together with Sc₅₇Ru₁₃ and Sc₅₇Rh₁₃ (Sc₅₇Rh₁₃ structure type)), and a solid solution based on α-scandium. The components of the isothermal section are eight single-phase regions, five three-phase fields (δ+<Sc₅Ru₃>+<Sc₂Ru>, <Sc₂Ru>+<Sc₁₁Ru₄> + η. <Sc₂Ru> + δ+η, >Sc₃Rh> + δ+η, >Sc₄₄Ru₇+<α-Sc>+η, and twelve two-phase regions. There is a difference from the phase equilibria at subsolidus temperatures in that at 930°C there are no equilibria related to the decomposition of the phase based on the compound Sc₂Rh (γ′), and they are replaced by new ones due to the formation of phases based on the compound Sc₄₄Ru₇ (θ) in the solid state.     

Alloy compositions and phase diagram for the Sc−Ru−Rh system. IV. Solidus surface of the Sc−ScRu−ScRh partial system

A projection has been constructed for the solidus surface of the partial, Sc−ScRu−ScRh system on the concentration triangle from data obtained by microstructure analysis, x-ray diffraction, microprobe analysis, differential thermal analysis, and the measurement of temperatures for the start of melting by the Pirani-Alterthum method. It is found that ternary compounds are not formed in this system. The solidus surface has regions representing solid solutions based on β-scandium and phases based on the binary compounds Sc₅Ru₃, Sc₂Ru, Sc₁₁Ru₄, Sc₂Rh, and Sc₃Rh, as well as ones for the δ and η phases (continous solid solution series formed between isostructural phases of CsCl type based on ScRu and ScRh as well as Sc₅₇Rh₁₃ based on Sc₅₇Ru₁₃ and Sc₅₇Rh₁₃). Other components of the solidus surface are twelve lineated surfaces, which bound two-phase volumes, and five isothermal surfaces, which correspond to nonvaiant four-phase equilibria involving the liquid, which occur at temperatures of 1150, 1055, 1045 (two equilibria), and 1000°C. Institute for Problems of Materials Science, Ukraine National Academy of Sciences, Kiev. Translated from Poroshkovaya Metallurgiya, Nos. 7–8(408), pp. 55–63, July–August, 1999.