Фазовая диаграмма системы Cu-Tl

К оглавлению: Другие диаграммы (Others phase diargams)


Cu-Tl (Copper-Thallium) D.J. Chakrabarti and D.E. Laughlin The equilibrium phases of the Cu-Tl system are (1) the liquid, L, which exhibits a region of immiscibility below 1250 C; (2) the fcc solid solution, ( Cu), which has restricted solubility of Tl (~0.28 at.% at 968 C); (3) the bcc solid solution, (bTl), with negligible solubility of Cu, which is stable below 304 C and undergoes an allotropic transformation between 234 and ~232 C to form; (4) the cph solid solution of virtually pure Tl, (aTl), which is stable down to 5 K. The Cu-Tl system exhibits a miscibility gap in the liquid from approximately 14.5 to 83 at.% Tl at the monotectic temperature of 968 C. Restricted solubilities in the solid state have also been reported. A eutectic transformation occurs at a composition near pure Tl. No metastable or intermediate phases have been reported. The assessed Cu-Tl equilibrium diagram is based primarily on the work of [06Doe], [46Rau], [52Kle], [55Sei], and [ 69Pre]. Thermodynamic modeling of the liquidus carried out by the present evaluators showed good agreement with the experimental boundary outside the miscibility gap, whereas inside the gap the agreement was not as good. The calculated temperature and composition values for both the monotectic and eutectic transformations are in good accord with the phase diagram. The solid solubility of Tl in (Cu), as measured by [46Rau] between 400 and 1050 C by X-ray and optical microscopy, reaches a maximum of ~0.28 at.% Tl at the monotectic temperature, with very limited solubility below 400 C. The invariant temperature for the alloy is 232 C [55Sel]. Below 232 C, the fcc (Cu) phase is in equilibrium with the cph (aTl) phase, and both phases have negligible solid solubility fields. 06Doe: F. Doerinckel, Z. Anorg. Chem., 48, 185-188 (1906) in German. 46Rau: E. Raub and A. Engel, Z Metallkd., 37, 76-81 (1946) in German. 52Kle: O.J. Kleppa, J. Am. Chem. Soc., 74, 6047-6051 (1952). 55Sei: W. Seith, H. Johen, and J. Wegner, Z. Metallkd., 46(11), 773-779 (1955) in German. 69Pre: B. Predel and M. Sandig., J. Mater. Sci., 4(1), 49-57 (1969) in German. Published in Bull. Alloy Phase Diagrams, 5(2), Apr 1984. Complete evaluation contains 2 figures, 5 tables and 16 references. 1