Фазовая диаграмма системы Ca-Y

К оглавлению: Другие диаграммы (Others phase diargams)


Ca-Y (Calcium-Yttrium) K.A. Gschneidner, Jr. and F.W. Calderwood The assessed phase diagram for the Y-Ca system is based on the work of [71Str], with adjustments to the melting and transition temperatures. They reported that immiscibility in the liquid state extended from ~23 to ~90 at.% Ca. They also reported a monotectic at 1180 C and a eutectic at 825 C. However, because the melting temperature of Y was reported to be 1501 C instead of the accepted value of 1522 C, and the melting temperature of Ca was reported to be 851 C instead of the accepted value of 842 C, the monotectic temperature on the assessed diagram has been raised 20 C to 1200 C, whereas the temperature of the eutectic was lowered 10 C to 815 C. These changes maintain the approximate (within с1 C) reported temperature differences between the melting point of the nearby metal and the monotectic or eutectic temperature in each case. The diagram of [71Str] included a solid horizontal line extending from Y to Ca at an unlabeled temperature of about 600 C. The field above this line is labeled "a + b," but this temperature is too high for the b = a transformation in (Ca), which should occur at virtually the identical temperature as the transformation in pure Ca, 443 C. Although not determined experimentally, the solubility of Ca in the RE metals ( other than Eu and Yb) must be less than in La, because of the difference in size factors and the difference in electronegativities. 71Str: V.E. Stroganova, V.F. Terekhova, and E.M. Savitskii, Rare Earth Metals and Alloys, E.M. Savitskii and V.F. Terekhova, Ed., Nauka, Moscow, 51 (1971) in Russian. Published in Bull. Alloy Phase Diagrams, 8(6), Dec 1987. Complete evaluation contains 2 figures, 1 table, and 1 reference. 1