Фазовая диаграмма системы Ho-Tl

К оглавлению: Другие диаграммы (Others phase diargams)


Ho-Tl (Holmium-Thallium) S. Delfino, A. Saccone, A. Palenzona, and R. Ferro The assessed phase diagram for the Ho-Tl system is based on the work of [87Del] . The melting points of the pure metals and the transformation temperatures have been adjusted slightly to conform to current accepted values. The equilibrium diagram contains five intermediate phases (Ho5Tl3, Ho5Tl3+x, HoTl, Ho3Tl5, and HoTl3) and four eutectic reactions. Metallography results suggest a homogeneity range of about 1 at.% for the intermediate phases except for HoTl3 (5 at.% Tl for HoTl). Ho5Tl3, HoTl, and HoTl3 melt congruently at 1360, 1230, and 910 C, respectively. Only Ho3Tl5 forms peritectically at 960 C. The formation mechanism of Ho5Tl3+x, phase, whose powder photograph showed clear similarities with that of the Ba5Pb3-type structure, was not determined; [87Sab] suggested a stoichiometry closer to 5:4 for this phase. No crystal structure experimental data have been reported. The maximum solid solubility of Tl in (Ho) is estimated to be about 5 at.% at the 1065 C eutectic temperature. The solid solubility of Ho in (bTl) and (aTl) is assumed to be negligible. Thermodynamics and magnetic properties of Ho-Tl alloys as well as the general properties of RE-Tl alloys have been discussed by [88Sac]. 87Del: S. Delfino, A. Saccone, G. Cacciamani, and R. Ferro, Z. Metallkd., 78, 344 (1987). 87Sab: N.A. Sabirzyanov, S.P. Yatsenko, and V.I. Kononenko, Izv. Akad. Nauk. SSSR, Met., 6, 168 (1987). 88Sac: A. Saccone, S. Delfino, and R. Ferro, J. Less-Common Met., 143, 1 (1988) . Submitted to the APD Program. Complete evaluation contains 1 figure, 1 table, and 5 references. 1