K. E. Kornienko

Alloy Constitution and Phase Equilibria in the Hf–Ru–Rh System. III. Solidus Surface of the Partial Ru–HfRu–HfRh–Rh System

The data obtained by metallography, X-ray diffraction, and electron microprobe and differential thermal analyses, as well as incipient melting points measured with the Pirani-Althertum method, are used to construct, for the first time, the solidus surface of the Hf–Ru–Rh system at 0–50 at.% Hf on the composition triangle. Ruthenium and rhodium solid solutions, ε and θ phases based on HfRh3 (AuCu3-type structure) and Hf3Rh5 (Ge3Rh5 type), and a continuous series of solid solutions between isostructural (CsCl type) phases based on the HfRu compound and its high-temperature modification (δ phase) take place in phase equilibria. Five single-phase surfaces corresponding to solid solutions based on components and binary phases, seven ruled surfaces bounding the two-phase volumes, and three isothermal planes formed by the mentioned phases in invariant four-phase equilibria with participation of liquid (at 1900, 1810, and 1720°C) are constituents of the solidus surface.

Alloy Structure and Equilibrium Phase Diagram for the Sc ― Ru ― Rh System. Part VI. Melting Diagram for the Sc ― ScRu ― ScRh Partial System

Data are used from metallography, x-ray diffraction, differential thermal analysis, and measurements on the temperatures for the start of melting in alloys obtained by the Pirani-Alterthum method to construct a projection of the liquidus surface and a crystallization scheme for alloys in the Sc ― ScRu ― ScRh partial system. The liquidus surface is formed by eight surfaces resulting from the primary crystallization of a solid solution based on β scandium and phases based on the compounds Sc5Ru3, Sc2Ru, Sc11Ru4, Sc2Rh and Sc3Rh, together with data on the continuous series of solid solutions formed between the isostructural phases based on the compounds ScRu and ScRh (CsCl structure type), Sc57Ru13 and Sc57Rh13 (Sc57Rh13 structure type). There are five nonvariant four-phase processes involving the liquid: incongruent ones L + ⇔ Sc(Ru, Rh) + at 1150°C, L + Sc(Ru, Rh) + Sc57(Ru, Rh)13 ⇔ (1055°C), L + Sc(Ru, Rh) ⇔ + (1045°C), L + Sc(Ru, Rh) ⇔ Sc57(Ru, Rh)13 + (1045°C), and the congruent ones L ⇔ + Sc57(Ru, Rh)13 + (1000°C). There are also twelve monovariant three-phase processes involving the liquid and a nonvariant three-phase reaction of eutectic type L ⇔ Sc(Ru, Rh) + Sc57(Ru, Rh)13 at a temperature close to 1065°C.

Constitution of Alloys and Phase Diagram of the Hf–Ru–Rh System. IV. Liquidus Surface and Melting Diagram of the Partial Ru–HfRu–HfRh–Rh System

Using the data obtained in study of the as-cast Hf–Ru–Rh alloys in the range 0–50 at.% Hf and considering the solidus surface constitution, physicochemical analysis techniques are employed to construct for the first time the liquidus surface of the Ru–HfRu–HfRh–Rh partial system onto the composition triangle, the melting diagram, and the reaction scheme reflecting processes during crystallization of the alloys. It is shown that five surfaces of primary crystallization of a continuous series of solid solutions between isostructural (CsCl-type) phases formed by compound HfRu and its high-temperature modification (δ phase), ruthenium and rhodium solid solutions, as well as the ε phase based on compound HfRh3 (AuCu3-type structure) and θ phase based on compound Hf3Rh5 (Hf3Rh5-type structure) are parts of the liquidus surface. Three invariant four-phase processes involving liquid take place at 1900, 1810, and 1720°C.

Alloy Constitution and Phase Equilibria in the Hf–Ru–Rh System. II. Liquidus Surface, Melting Diagram, and Vertical Sections of the Partial Hf–HfRu–HfRh System

According to the constitution of the solidus surface in the Hf–Ru–Rh system over the composition range 50−100 at.% Hf and the data obtained in studying the as-cast alloys by physicochemical analysis techniques, we constructed, for the first time, the liquidus surface of the partial Hf–HfRu–HfRh system on the composition triangle and its melting diagram. The vertical sections at 5 at.% Ru, 10 at.% Rh, and 75 and 80 at.% Hf at the ratio Ru : Rh = 1 : 1 are presented. The processes that occur when the alloys are crystallized are shown in the reaction scheme. The primary crystallization regions for a continuous series of solid solutions between isostructural (CsCl type) phases formed by the HfRu compound and its high-temperature modification (δ phase) as well as β-Hf and γ-Hf2Rh (Ti2Ni type) solid solutions are parts of the liquidus surface. An invariant four-phase equilibrium involving liquid, LU + δ ⇆ γ + , is observed at 1373°C in the system.

The Constitution of Alloys and Phase Diagram of the Ternary Al–Cr–Pt System at 50–100 at.% Pt. I. Solidus Surface and Isothermal Section in the Al–Cr–Pt System at 1350 C in the Range 50–100 at.% Pt

The results of high-temperature diffraction, metallography, X-ray diffraction, electron microprobe analysis, and differential thermal analysis are used to specify the constitution of the Al–Pt system in the near-equiatomic range. The solidus surface is constructed for the first time on the composition triangle, and the constitution of the isothermal section at 1350°C in the range 50–100 at.% Pt of the Al–Cr–Pt ternary system is specified. The solidus surface consists of six single-phase surfaces corresponding to the ternary τ1 phase (unknown structure), solid solutions based on platinum, and four binary phases existing in the Al–Pt system; nine ruled surfaces bounding two-phase volumes; and four isothermal planes forming invariant four-phase equilibria with participation of a liquid phase. When temperature decreases from subsolidus to 1350°C, stability of the phase based on the <(Al, Cr)Pt2> compound (low-temperature modification) increases substantially. This phase takes part in equilibria with other intermediate phases and with the Pt-based solid solution.

Constitution of alloys and phase diagram of the Al–Ti–Rh system. III. Solidus surface of the Ti–TiRh–AlRh–Al partial system

The data obtained by metallography, x-ray diffraction, electron microprobe and differential thermal analyses as well as by Pirani–Alterthum incipient melting technique are used to construct the solidus surface projection of the Ti–TiRh–AlRh–Al partial system onto the composition triangle for the first time. The participation of two ternary compounds (τ1, Al67Ti27Rh6, with AuCu3-type structure, and τ2, Al49.6Ti27.1Rh23.3, with Th6Mn23+1-type structure) in phase equilibria is confirmed. Thirteen single-phase surfaces corresponding to solid solutions based on components and to the phases based on binary and ternary compounds are found on the solidus surface. This surface also contains 25 ruled surfaces bounding two-phase volumes as well as 13 isothermal planes that are constituents of invariant four-phase equilibria.

CONSTITUTION OF ALLOYS AND PHASE DIAGRAM OF THE Al-Ti-Rh SYSTEM. IV. MELTING DIAGRAM OF THE Ti-TiRh-AlRh-Al PARTIAL SYSTEM

Based on constitution of the solidus surface of the Ti–TiRh–AlRh–Al partial system and on metallography, X-ray diffraction, electronic microprobe, and differential thermal analyses of its ascast alloys, the liquidus surface projection of the system is constructed onto the concentration triangle for the first time and the processes occurring in the crystallization of its alloys are studied. This has given an opportunity to construct the melting diagram of the Ti–TiRh–AlRh–Al partial system for the first time. Its liquidus surface is completed with 13 surfaces of primary crystallization of solid solutions based on components and phases based on binary and ternary compounds. In the Ti–TiRh–AlRh–Al partial system, there are 13 invariant four-phase equilibria involving liquid as well as nine invariant three-phase equilibria, eight of them being eutectic and one peritectic.

Alloy Structure and Equilibrium Phase Diagram for the Sc–Ru–Rh System. Part 7. Polythermal Sections in the Sc–Ru–Rh System

DTA, XRD, metallography, and electron-probe microanalysis have been applied to study phase compositions of cast and annealed alloys (annealing at subsolidus temperatures of 1400°C (composition range 0-50 at.% Sc) and 930°C (composition range 50-100 at.% Sc)) and construct polythermal sections for the Sc ― Ru ― Rh ternary system on the isoconcentrates 75 at.% Sc, 65 at.% Rh, and beam Ru:Rh = 1:1, as well as isoconcentrates for 5.0 ± 0.3 at.% Ru and 5 at.% Rh in the region of 50-100 at.% Sc. The sections reveal characteristic features of the phase diagram structure for this ternary system, in particular temperature ranges for crystallization and the types of phase transformation within them.

Alloy behavior and the Sc-Ru-Rh phase diagram. Part 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 concentration triangle. It is found that ternary compounds are not formed. The solidus surface is made up of five surfaces for the primary crystallization of solid solutions based on ruthenium and rhodium together with phases based on the compounds ScRu2, ScRh3, and the 6 phase (a continuous series of solid solutions between isostructural phases of CsCl type based on ScRu and ScRh), together with seven lineated surfaces, which enclose two phase volumes, and three isothermal areas, which relate to nonvariant four-phase equilibria involving the liquid: L — + + 6 (1650°C), L + ⇌ + (1640°C) and L ⇌ + ⇌ + (1520°C).

Phase Equilibria in the Aluminum Corner of the Al–Ti–Pt System

A series of physicochemical analysis techniques are employed to study the phase equilibria in the aluminum corner of the Al–Ti–Pt system at subsolidus temperatures and in the alloy crystallization process. It has been established for the first time that a ternary τ1 phase (AuCu3 structural type) forms by peritectic reaction L + + ⇄ τ1 at 1405°C. On the solidus surface in the studied composition range at 1405, 1310, 1275, 1060, 925, 820, and 660°C, there are seven isothermal planes that participate in invariant four-phase equilibria involving the liquid phase, three of them being peritectic and the others transitional.