Фазовая диаграмма системы Ag-Ce

К оглавлению: Другие диаграммы (Others phase diargams)

Ag-Ce (Silver-Cerium) K.A. Gschneidner, Jr. and F.W. Calderwood Although the Ag-Ce system has been studied extensively, there is no complete agreement on the phase boundaries. The assessed Ag-Ce phase diagram is based on a review of select experimental data [75Del, 80Heu, 83Sta, 84Sta]. The melting points and transformation temperatures of the pure metals have been adjusted to agree with the accepted values in [Gschneidner]. Ag2 forms peritectically from the melt and Ag53Ce14 at 855 C. The Ce concentration of the melt at the peritectic temperature is 35 at.%. The room- temperature form of Ag2Ce has the CeCu2-type orthorhombic structure. AgCe melts congruently at a temperature between 855 C and 885 C. The room- temperature form of AgCe has the cubic CaCl-type structure. [75Del] observed a thermal effect below the AgCe-Ce eutectic at 455 C. [84Sta] reported a thermal effect at 485 C in both two-phase fields adjacent to AgCe, which they attribute to a phase transformation in AgCe. This feature is shown in the assessed diagram. Three eutectics exist in this system. Ag forms a eutectic with Ag4Ce at 10 at.% Ce and 798 C. A second eutectic occurs between Ag2Ce and AgCe at 43 at.% Ce and 780 C. The other eutectic forms between AgCe and Ce at 81 at.% Ce and 508 C. The solid solubility of Ce in Ag is 0.04 to 0.06 с 0.005 at.% [70Gsc]. Addition of Ag to (dCe) stabilized the high-temperature phase at temperatures slightly below the normal gCe = dCe transformation temperature (726 C) and decomposes via an inverted peritectic reaction (dCe = L + gCe) at 710 C and 98 at.% Ce [84Sta]. The maximum solid solubility of Ag in (dCe) is ~2 at.% at 505 C. 70Gsc: K.A. Gschneidner, Jr., O.D. McMasters, D.G. Alexander, and R.F. Venteicher, Metall. Trans., 1, 1961 (1970). 75Del: S. Delfino, R. Ferro, R. Capelli, and A. Borsese, J. Less-Common Met., 41, 59 (1975). 80Heu: T. Heumann and A. Pr‚val, J. Less-Common Met., 76, 263 (1980). 83Sta: I. Stapf and H. Jehn, J. Less-Common Met., 92, 167 (1983). 85Sta: I. Stapf and H. Jehn, J. Less-Common Met., 98, 173 (1984). Published in Bull. Alloy Phase Diagrams, 6(5), Oct 1985. Complete evaluation contains 1 figure, 1 table, and 16 references. 1