Фазовая диаграмма системы Au-Tl

К оглавлению: Другие диаграммы (Others phase diargams)


Au-Tl (Gold-Thallium) H. Okamoto and T.B. Massalski The equilibrium phases of the Au-Tl system are (1) the liquid, L; (2) the fcc terminal solid solution, (Au), with less than 1 at.% solid solubility of Tl; ( 3) the high-temperature bcc (bTl) terminal solid solution; and (4) the low- temperature cph (aTl) terminal solid solution. The solid solubility of Au in either allotropic form of (Tl) is less than 0.5 at.%. The temperature of the allotropic transformation in pure Tl is 230 C. A metatectic reaction (bTl) = L + (aTl) occurs in Tl-rich alloys at 217 с 3 C and at compositions within less than 0.5 at.% Au. The phase diagram calculated on the basis of thermodynamic experimental data alone, obtained in the temperature range between 600 and 800 C, agrees with the experimentally determined phase diagram, but shows a shift in the eutectic point of about 5 at.% to a higher Tl concentration. Slightly modified thermodynamic functions, utilizing optimization de-rived from the liquidus curves, can express the phase diagram even more accurately and have been used to draw the liquidus in the assessed diagram. The present diagram is based primarily on the work of [05Lev] and [78Eva], with review of the work of [ 51Kle], [56Kle], and [76Kam]. 05Lev: M. Levin, Z. Anorg. Chem., 45, 31-38 (1905) in German. 51Kle: O.J. Kleppa, J. Am. Chem. Soc., 73, 385-390 (1951). 56Kle: O.J. Kleppa, J. Phys. Chem., 60, 446-452 (1956). 76Kam: K. Kameda, S. Sakairi, and Y. Yoshida, J. Jpn. Inst. Met., 40(4), 387- 392 (1976) in Japanese. 78Eva: D.S. Evans and A. Prince, Met. Sci., 12(8), 386-387 (1978). Published in Phase Diagrams of Binary Gold Alloys, 1987, and Bull. Alloy Phase Diagrams, 4(2), Sep 1983. Complete evaluation contains 8 figures, 3 tables, and 15 references. 1