Фазовая диаграмма системы As-Pb

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As-Pb (Arsenic-Lead) N.A. Gokcen The equilibrium phases of the As-Pb system are (1) the liquid, L; and (2) the solids (aAs) and (Pb), both containing very small amounts of dissolved coexisting phases. There are no intermediate phases. The assessed diagram was obtained by thermodynamic modeling of the experimental data. The phase boundaries in the assessed diagram have been drawn according to the data of [ 14Hei], [73Hut], and [74Sul], with the emphasis on the latter two references. The liquidus from 0 to 10 at.% Pb is based on an equation for the depression of the freezing point of As. The melting point of As is 817 с 1 C at 35.8 atm (1 atm = 101 325 Pa) [89Gok]. The melting point of hypothetically existing aAs at 1 atm would be lower by less than 0.15 C. Data of [73Hut] and [74Sul] are used in drawing the liquidus from about 50 at.% Pb to the eutectic, with the emphasis on the data of [73Hut]. The assessed phase diagram is shown at 1 atm of pressure up to about 70 at.% As, above which gaseous As pressure is higher. The pressures up to 36 atm are not expected to affect the liquidus [77Rap]. The solubility up to 100 C is immeasurably small [29Sel]. The solid solubility of Pb in (As) is very small [14Hei] and is estimated to be less than 0.1 at.% Pb in the assessed diagram. The eutectic composition is nearly independent of pressure, but the eutectic temperature increases to 337.9 C at 10 kbar and 421.8 C at 35 kbar [77Rap]. The difference in temperatures between the eutectic and the liquidus at 90 at.% Pb remains 20 C and independent of pressure. The vapor pressure of As is sufficiently high over the alloys containing more than 60 at.% As. Therefore, the pressure of gaseous As (As4) can be measured with quartz Bourdon or spoon gauge. New cooling curves in this range would also be very useful in obtaining a phase diagram consistent with its experimental thermodynamic properties. 14Hei: W. Heike, Z. Metallogr., 6, 49-57 (1914) in German. 29Sel: K.S. Seljesater, Trans. AIME, 573-580 (1929). 73Hut: S.E. Hutchison and E.A. Peretti, J. Less-Common Met., 30, 306-308 (1973) . 74Sul: D.M. Suleimanov, A.N. Mamedov, and A.A. Kuliev, Izv. V.U.Z. Khim. Khim. Tekhnol., 17(3), 365-367 (1974) in Russian. 77Rap: E. Rapoport, J.B. Clark, and P.W. Richter, J. Less-Common Met., 55, 121- 124 (1977). 89Gok: N.A. Gokcen, Bull. Alloy Phase Diagrams, 10(1), 11-22 (1989). Published in Bull. Alloy Phase Diagrams 11(2), Apr 1990. Complete evaluation contains 3 figures, 3 tables, and 20 references. 1