Фазовая диаграмма системы Hg-Ti

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Hg-Ti (Mercury-Titanium) J.L. Murray Only limited portions of the Ti-Hg diagram are experimentally accessible, and these represent phase boundaries in equilibrium with the vapor. The assessed diagram is based on the vapor pressure and X-ray study of [73Lug]. Only the range 0 to 700 C has been investigated, and the high-temperature bcc (bTi) phase therefore does not appear. The solubility of Hg in (aTi) is sufficiently low that it cannot be determined by lattice parameter measurements. [54Pie] identified two allotropes of Ti3Hg; the high-temperature form had the L12 structure. However, [68Kur] showed that this phase is actually an oxide phase with the perovskite structure. Structural data on TiHg are from [54Pie] and [70Pus], and the phase equilibria are from [73Lug]. Both [54Pie] and [70Pus] stated that the alloys showed a pronounced tendency to decompose at room temperature. According to [73Lug], there is a narrow vertical two-phase region (TiHg + X), and TiHg has only a narrow range of homogeneity. Further work will probably suggest a better interpretation of the vapor pressure measurements. The assessed diagram provisionally reproduces that of [73Lug]. [73Lug] speculated on the presence of TiHg3 from the decomposition of amalgams stored for several months and determined its decomposition temperature to be 128 C by differential thermal analysis. If TiHg3 is an equilibrium phase, the (Hg) liquidus must represent a metastable equilibrium of the liquid with TiHg. The solubility of Ti in liquid Hg has been determined by chemically analyzing the equilibrated, filtered liquid [63Jan, 67Wee]. The measurements of [63Jan] extend over the range 15 to 575 C. Different filtration techniques were used above and below the boiling point of Hg, and the two sets of data lie on a single straight line in a log x versus 1/T plot. [67Wee] worked in a smaller temperature range, and their data show more scatter. The assessed liquidus is based on [63Jan]. 54Pie: P. Pietrokowsky, Trans. AIME, 200, 219-226 (1954). 63Jan: G. Jangg and H. Palman, Z. Metallkd., 54(6), 364-369 (1963) in German. 67Wee: J.R. Weeks, Corrosion, 23, 98-106 (1967). 68Kur: F. Kurka and P. Ettmayer, Monatsh. Chem., 99, 1836-1838 (1968) in German. 70Pus: M. Puselj and Z. Ban, Z. Naturforsch., 25(2), 315 (1970). 73Lug: E. Lugscheider and G. Jangg, Z. Metallkd., 64(10), 711-715 (1973) in German. Published in Phase Diagrams of Binary Titanium Alloys, 1987. Complete evaluation contains 2 figures, 1 table, and 9 references. 1