Фазовая диаграмма системы Ba-Pd

К оглавлению: Другие диаграммы (Others phase diargams)

Ba-Pd (Barium-Palladium) H. Okamoto The assessed Ba-Pd phase diagram is primarily based on thermal and metallographic investigations performed by [71Dmi]. The Ba-Pd phase diagrams proposed by [70Sav] and [71Dmi] for the range between BaPd2 and pure Pd are quite different. The diagram proposed by [71Dmi] based on differential thermal analysis data is preferred here. The BaPd5 liquidus in [70Sav] is very asymmetric, and a straight line on the Ba-rich side requires an unlikely form in the Gibbs energy function for the liquid phase [ 91Oka]. Moreover, the form of liquidus depends on a single melting point data of BaPd5 determined by using the "drop" method with an optical pyrometer, and is not supported by other data points. The congruent melting temperature of BaPd2 is 1360 C [71Dmi]. The peritectic melting of BaPd2 at 1290 с 25 C proposed by [70Sav] may be speculative because no data points are given supporting a peritectic reaction. The peritectic melting point of BaPd5 is 1260 C [71Dmi]. [70Sav] observed the melting at 1620 с 25 C. The form of BaPd5 liquidus speculated by [70Sav] is very unlikely as mentioned above and not accepted here. The L = (Pd) + BaPd5 eutectic point was proposed by [70Sav] at 88 at.% Pd and 1225 с 10 C. However, the eutectic reaction was not observed by [71Dmi]. Although the diagram proposed by [71Dmi] is generally preferred to that of [ 70Sav] as described above, the relationship between the initial slopes of the liquidus and the solidus of (Pd) is thermodynamically inconsistent (see [91Oka] ). If the solid solubility of Ba in (Pd) is negligible as shown, the initial slope of the liquidus as proposed by [70Sav] is more plausible. If the initial slope proposed by [71Dmi] is correct, the solid solubility of Ba in (Pd) cannot be negligibly small. No conclusive diagram can be drawn in this region due to the lack of data to support either situation. 58Woo: E.A. Wood and V.B. Compton, Acta Crystallogr., 11, 429-433 (1958). 66Bru: G. Bruzzone, Atti Accad. Naz. Lincei, Cl. Sci. Fis. Mat. Natur. Rendiconti, 41(1-2), 90-96 (1966) in Italian. 70Sav: E.M. Savitskiy, V.P. Polyakova, and E.M. Khorlin, Izv. Akad. Nauk SSSR, Met., (6), 143-145 (1970) in Russian; TR: Russ. Metall., (6), 88-89 (1970). 70Zhu: N.N. Zhuravlev, N.P. Esaulov, and I.V. Rall, Kristallografiya, 15(2), 374-376 (1970) in Russian; TR: Sov. Phys. Crystallogr., 15(2), 315-316 (1970). 71Dmi: V.N. Dmitrieva, N.P. Esaulov, N.N. Zhuravlev, and V.M. Rozhdestvenskii, Tr. Inst. Fiz. Met., 28, 58-68 (1971) in Russian. 74Ian: A. Iandelli and A. Palenzona, J. Less-Common Met., 38(1), 1-7 (1974). 91Oka: H. Okamoto and T.B. Massalski, J. Phase Equilibria, 12(2), 148-168 ( 1991). Submitted to the APD Progrm. Complete evaluation contains l figure, 2 tables, and 5 references. 1