Фазовая диаграмма системы Ag-Hg

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Ag-Hg (Silver-Mercury) M.R. Baren The general form of the assessed equilibrium phase diagram for the Ag-Hg system was determined by [31Mur] and [31Pre], with review of the work of [ 38Day], [58Ray], and [61Kin]. Accurate evaluation of this system is difficult because of the difference in physical properties of the two elements. Hg has a boiling point well below the melting point of Ag. In addition, the low freezing point of Hg made it difficult to use ordinary metallographic techniques to examine Hg-rich alloys that contained a liquid constituent to room temperature. The liquidus curve for compositions between 0 and 91.1 at.% Hg is due to [ 31Mur]. Additions of Hg to Ag cause a reduction in the initial freezing point down to the freezing of Hg. There was no indication of a eutectic. The liquidus curve between 200 and 300 C has not been determined in detail. The solidus and solid solubility curve of Hg in Ag are due mainly to the work of [30Day], who determined the maximum solubility of Hg in Ag to be 37.3 at.% at 276 C. They also found that the solubility decreased slightly with decreasing temperature to about 36.5 at.% Hg at 100 C. [31Mur] and [31Pre] established the existence of the two intermediate phases, z and g, both having restricted composition ranges. The z phase crystallizes in a cph structure with a composition range of approximately 43.50 to 46.00 at. % Hg [61Kin]. At 276 C, the z phase dissociates upon heating into liquid and the a phase in a peritectic reaction. The g bcc phase has a composition range of approximately 55.7 to 56.8 at.% Hg [31Mur]. Upon heating, the g phase dissociates at 127 C into liquid and the z phase, also in a peritectic reaction. The most probable formula for the g phase is Ag11Hg15. [64Mer] found that the g phase becomes superconducting with a transition temperature of -272.36 C. Their sample, which had a composition of 56.2 at.% Hg, was determined by X-ray diffraction to be single phase. 31Mur: A.J. Murphy. J. Inst. Met., 46, 507-522 (1931). 31Pre: G.D. Preston, J. Inst. Met., 46, 522-527 (1931). 38Day: H.M. Day and C.H. Matewson, Trans. AIME, 128, 261-280 (1938). 58Ray: H.W. Rayson and L.D. Calvert, J. Inst. Met., 87, 88-90 (1958-1959). 59Ato: M. Atoji, J.E. Schirber, and C.A. Swenson, J. Chem. Phys., 31(6), 1628- 1629 (1959). 61Kin: H.W. King and T.B. Massalski, Philos. Mag., 6, 669-682 (1961). 64Mer: M.F. Merrian, Phys. Lett., 9(2), 101-102 (1964). 71And: P. Anderson and S.J. Jensen, Scand. J. Dent. Res., 79, 466-471 (1971). Submitted to the APD Program. Complete evaluation contains 2 figures, 6 tables, and 30 references. Special Points of the Ag-Hg System