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Phase equilibria during solidification in the Al-Cr-Co system in the range of compositions 0-70 at.% Al were studied using optical microscopy, scanning electron microscopy, electron probe microanalysis, differential thermal analysis and x-ray diffraction. Solidus and liquidus surfaces, a melting diagram as their superposition, a Scheil diagram for solidification, as well as series of isopleths were constructed for the first time. Solid solutions based on Cr, αCo, Cr5Al8 (γ3 and γ1 phases), CoAl, Co2Al5 binary compounds and the ternary compound τ5 take part in phase equilibria. The monoclinic ternary compound τ5 forms by peritectic reaction L + γ1 + Co2Al5 ↔ τ5 at 1065 °C. Four invariant four–phase reactions and one invariant three–phase reaction involving liquid take place at 1280, 1175, 1110, 1065 and about 1480 °C, respectively. Isopleths 10, 20, 30 and 40 at.% Al as well as 40 at.% Cr demonstrate peculiarities of the phase diagram. [ABSTRACT FROM AUTHOR]

Physicochemical analysis results for alloys in the Al–Ti–Pt system at 0–50 at.% Pt that were cast and annealed at subsolidus temperatures are used to construct for the first time vertical sections at 7, 25, and 35 ± 1 at. Pt of this system taking into account the constitution of its melting diagram. The congruent crystallization of τ3, τ 4, and τ8 compounds and incongruent crystallization of τ2 and τ5 compounds are confirmed. Changes from incongruent to congruent crystallization of the solid solutions based on binary Al3Pt2, Al2Pt, and TiAl phases in transition to the ternary system are shown. [ABSTRACT FROM AUTHOR]

The liquidus surface of the Al–Ti–Pt system has been constructed for the first time on the composition triangle based on studies of the structure and phase composition and measurement of the liquidus temperatures for the as-cast alloys in the composition range 0–50 at.% Pt produced using a series of techniques. The liquidus surface has 23 primary crystallization fields corresponding to τ1–τ9 and τ11 ternary phases and binary phases formed in the boundary systems and to solid solutions based on components. The extension of these fields and the positions of univariant curves and invariant points have been determined. The liquidus surface exists in the temperature range from 1830°C (corresponding to congruent melting of TiPt compound) to 655°C (temperature of the l ⇄ + 21Pt5> eutectic in the binary Al–Pt system). [ABSTRACT FROM AUTHOR]

The nature of phase equilibria has been examined for the first time in the Al–Ti–Pt system in the range 0–50 at.% Pt at subsolidus temperatures. Besides the τ1, τ2, and τ3 ternary compounds with AuCu3, Th6Mn23+1, and MgZn2 lattices known from the literature, eight more compounds form in the system at subsolidus temperatures. The structural type is known for three of these compounds. They are τ4 (ZrBeSi), τ5 (CrFe), and τ6 (defective structure of Au4Al type). There are 31 isothermal planes on the solidus surface. All planes are formed with participation of ternary compounds and solid solutions based on binary compounds present in the boundary systems. The highest temperature in this composition range corresponds to the congruent melting of the TiPt phase (1830°C) and the lowest to eutectic l ⇄ + in the binary Al–Pt system (655°C). [ABSTRACT FROM AUTHOR]