Фазовая диаграмма системы Sb-Zr

К оглавлению: Другие диаграммы (Others phase diargams)

Sb-Zr

Sb-Zr (Antimony-Zirconium) H. Okamoto The assessed Sb-Zr phase diagram is a compromise of contradictory reports. [ 51Rus] proposed a partial phase diagram in which SbZr2 is shown as the Zr- richest compound. Because of its similarity in crystal structure, this compound in [51Rus] has been identified in this evaluation as Sb3Zr5. Actually, Sb3Zr5 may exist at an off-stoichiometric composition of 64 at.% Zr [63Bol], closer to SbZr2. The melting point is about 1900 C [51Rus]. Four additional compounds were found subsequently: Sb2Zr [64Hul], bimorphic SbZr2 [65Ros], and SbZr3 [64Sch]. However, no phase relationships between these newly discovered phases have been reported. The assessed liquidus is nearly identical to that of [51Rus]. The form of the liquidus may be somewhat different in the range between Sb3Zr5 and (Zr), where additional Zr-rich phases were found. The solubility limit of Zr in (aSb) is unknown. The presence of bSbZr2 and aSbZr2 may have to be confirmed because their crystal structures are barely known and the composition is very close to that of Sb3Zr5. The maximum solubility limits of Sb in (bZr) and (aZr) are 11 and 1.9 at.% [ 51Rus]. However, these values were considered to be approximate because of C contamination and are not accepted here. The solubilities of Sb in (bZr) and ( aZr) were redetermined by [58Bet]. Although the Zr metal used by [58Bet] was not very pure, as indicated by double transformations at 857 and 873 C, the influence of impurity on the solubility of Sb is assumed to be insignificant and the values of [58Bet] are tentatively accepted in the assessed diagram. The composition of (bZr) at the L = SbZr3 + (bZr) eutectic temperature (1430 C in the assessed diagram) is shown at 92 at.% Zr, which was obtained by an extrapolation of a plot of log (solubility of Sb in (bZr)) vs 1/T. [Elliott] estimated the peritectoid transformation temperature of (bZr) to (aZr) to be 875 C from an impurity-induced ternary phase diagram in [58Bet]. The same peritectoid temperature observed by [51Rus] was ~980 C, which appears to be too high because the allotropic transformation temperature of Zr at 925 C was also much higher than the assessed value. 51Rus: R.F. Russi and H.A. Wilhelm, U.S. At. Energy Comm., AECD-3610 (1951) as quoted in [Hansen]. 58Bet: J.O. Betterton, Jr., and W.M. Spicer, Trans. AIME, 212(8), 456-457 ( 1958). 61Bet: J.O. Betterton, Jr. and D.S. Easton, U.S. At. Energy Comm., ORNL-3160, 3-4 (1961); J. Met., 13, 86-87 (1961). 62Sch: K. Schubert, H.G. Meissner, M. Porzschke, W. Rossteutscher, and E. Storz, Naturwissenschaften, 49(3), 57 (1962) in German. 63Bol: H. Boller and E. Parthe, Monatsh. Chem., 94, 225-226 (1963) in German. 64Hul: F. Hulliger, Nature, 204, 991 (1964). 64Sch: K. Schubert, A. Raman, and W. Rossteutscher, Naturwissenschaften, 51(24) , 506-507 (1964) in German. 65Ros: W. Rossteutscher and K. Schubert, Z. Metallkd., 56(11), 813-822 (1965) in German. 68Ebe: D. Eberle and K. Schubert, Z. Metallkd., 59, 306-308 (1968) in German. 72Kje: A. Kjekshus, Acta Chem. Scand., 26(4), 1633-1639 (1972). Submitted to the APD Program. Complete evaluation contains 1 figure, 3 tables, and 10 references. 1

 




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