Фазовая диаграмма системы Ag-Tb

К оглавлению: Другие диаграммы (Others phase diargams)


Ag-Tb (Silver-Terbium) K.A. Gschneidner, Jr. and F.W. Calderwood The assessed phase diagram for the Ag-Tb system is based primarily on the work of [76Del], with some modifications. The eutectic temperature for Ag with Ag51Tb14, the Ag-rich phase, is 801 C, as reported by [70Gsc], who used purer rare earth materials. The melting point of Ag has been raised from 960 to 962 C, to agree more closely with the accepted value (961.93 C) [Melt]. The maximum solid solubility of Tb in (Ag) was found to be 1.12 at.% [70Gsc]. There is no information on the solid solubility of Ag in (Tb), or on the effect of additions of Ag on the a to b transition in Tb. [76Del] reported three intermetallic compounds, all melting congruently: Ag51Tb14 (melting point, 985 C), Ag2Tb (melting point, 915 C), and AgTb ( melting point, 1145 C). Four eutectics were reported: Ag-Ag51Tb14 (805 C, which has been changed to 801 C in the assessed diagram, 11 at.% Tb), Ag51Tb14-Ag2Tb (885 C, 31.5 at.% Tb), Ag2Tb-AgTb (900 C, 35 at.% Tb), and AgTb-Tb (860 C, 75 at.% Tb). The Ag-rich phase, Ag51Tb14, was reported to have the same hexagonal structure as Ag51Gd14. In contrast to the Ag51RE14 phase of the light rare earths, Ag51Tb14 does not undergo a large supercooling when solidifying from the melt. The Ag2Tb phase has the tetragonal MoSi2-type structure and was reported to correspond to an exact stoichiometric ratio, whereas the compound AgTb seems to show a stoichiometry slightly rich in Tb. [77Bou] studied bulk magnetic properties of an amorphous Ag-Tb alloy that was prepared by melting Tb (99% pure) and Ag (99.99% pure) in an argon atmosphere. Electron microprobe analysis showed the composition to be Ag48Tb52 with no concentration gradient in the layer deposited. The amorphous nature of the alloy was established by X-ray and electron diffraction techniques. 70Gsc: K.A. Gschneidner, Jr., O.D. McMasters, D.G. Alexander, and R.F. Venteicher, Metall. Trans., 1, 1961-1971 (1970). 76Del: S. Delfino, A. Saccone, A. Borsese, and R. Ferro, Z. Metallkd., 67(6), 392-394 (1976). 77Bou: B. Boucher, Phys. Status Solidi (a), 40, 197 (1977). Published in Bull. Alloy Phase Diagrams, 6(2), Apr 1985. Complete evaluation contains 1 figure, 1 table, and 14 references. 1