Фазовая диаграмма системы Ag-Yb

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Ag-Yb (Silver-Ytterbium) K.A. Gschneidner, Jr. and F.W. Calderwood The assessed phase diagram for the Ag-Yb system is based primarily on the work of [70Pal], with some modifications. The melting point of the pure metals and the b to g transition in Yb were brought into agreement with the accepted values listed in [Gschneidner]. The eutectic temperature for Ag-Ag9Yb2 (685 C) and the solid solubilityof Yb in (Ag) (1.92 at.%) are taken from [70Gsc]. [70Gsc] found the Ag-rich compound in this system to be Ag5Yb, with the same structure as the high-temperature form of Ag5La and the phase Ag5Pr. [70Pal] reported six intermediate phases: Ag3Yb5, Ag2Yb3, AgYb, Ag2Yb, Ag7Yb2, and Ag9Yb2. Structure analysis of the last phase was not completed, but the formula Ag9Yb2 was assigned to it on the basis of differential thermal analysis data, metallographic evidence, and the fact that a 9-to-2 compound is known in the Ag-Ca system. AgYb, Ag2Yb, and Ag7Yb2 melt congruently at 724, 661, and 749 C, respectively. Eutectics were observed in four of the subsystems: Ag-Ag9Yb2, at 685 C and 13 at.% Yb; Ag7Yb2-Ag2Yb, at 646 C and 31.5 at.% Yb; Ag2Yb-bAgYb, at 589 C and 39.5 at.% Yb; and Ag3Yb5-Yb, at 446 C and 79 at.% Yb. The AgYb compound transforms from the room-temperature structure (orthorhombic FeB type) to a high-temperature modification (cubic CsCl type) at 456 C. The orthorhombic CeCu2-type structure was the only one reported for the Ag2Yb phase in this investigation. No appreciable solid solubility of Ag in (Yb) was observed [70Pal], and the presence of Ag did not affect the b = g transformation of Yb. Yb was observed to retain its divalent nature throughout the entire composition range, showing a strong similarity to Ca in the Ag-Ca system. 70Gsc: K.A. Gschneidner, Jr., O.D. McMasters, D.G. Alexander, and R.F. Venteicher, Metall. Trans., 1, 1961-1971 (1970). 70Pal: A. Palenzona, J. Less-Common Met., 21, 443-446 (1970). Published in Bull. Alloy Phase Diagrams, 6(2), Apr 1985. Complete evaluation contains 1 figure, 1 table, and 9 references. 1