Фазовая диаграмма системы Fe-Y

К оглавлению: Другие диаграммы (Others phase diargams)

Fe-Y

Fe-Y (Iron-Yttrium) W. Zhang, G. Liu, and K. Han [61Dom] investigated the entire Fe-Y system with 99% pure Y and 99.9% pure Fe. [61Gsc] thought that the experimental technique employed in [61Dom] did not justify showing the liquidus as a solid line, and [82Kub] made minor revisions to phase stoichiometries to bring the diagram into accord with results from more recent crystallographic studies. The assessed diagram is essentially the diagram proposed by [61Dom], with the revisions of [82Kub]. There are four compounds in this system-Fe17Y2, Fe23Y6, Fe3Y, and Fe2Y-with the first three compounds melting congruently. The compound Fe5Y with the CaCu5 structure reported by [61Gsc] could not be confirmed by later experiments [71Tay]. Hellawell reported that 1 at.% Y lowers the g/d Fe transformation temperature by 3 C [61Gsc]. The effect of additions of Y on a/g Fe transformation is not known [82Kub]. The terminal solid solubility of Y in Fe is less than 1 wt.% [ 61Gsc]. The equilibrium solubility of Fe in Y is less than 0.1 at.%, although as much as 3 at.% Fe could be dissolved interstitially in cph Y in rapidly quenched Y-rich alloys [81Ten]. A g loop (similar to the Fe-Cr system) was reported by [61Dom] to exist at a composition less than 1 wt.% Y. However, no further experimental information is available. Such a g loop is not shown in the assessed diagram. Fe17Y2 melts congruently at 1400 с 25 C [61Dom]. Two modifications exist-the rhombohedral Th2Zn17 type and hexagonal Ni17Th2 type. Because samples annealed at 1000 C for 15 days contained both types of Fe17Y2 and because splat-cooled samples contained only the hexagonal type [66Bus], the Ni17Th2 type should be considered the high-temperature modification of Fe17Y2. Fe3Y melts congruently, whereas Fe2Y is formed peritectically. Fe2Y has a small composition range, because a slight decrease of the lattice parameter (0. 0004 nm) was found between the 65.0 and 68.0 at.% Fe alloys after annealing at 870 C for 125 h [60Bea]. The compound was also found after annealing at 700 or 900 C [61Dwi]. [82Ten] investigated the crystallization of the metallic glass Fe0.32Y0.66, prepared by levitation melting of high-purity components and splat cooling. The crystallization of this glass occurs in two distinct steps associated with the formation of cph Y and the Laves phase Fe2Y. A bcc form of elemental Y was observed in Fe-Y alloys that were rapidly quenched by melt spinning, and the compositions in which the bcc Y phase is formed are near the eutectic shown in the Fe-Y phase diagram (34.6 at.% Fe) [82Ten]. The Curie temperature of Fe2Y was reported to be 535 K [61Gsc]. The Curie temperature of Fe23Y6 is 481 K [86Chu], which is in good agreement with the results of [79Bes] (478 K) and [84Her] (484 K). An Fe sublattice model accurately describes the temperature dependence of the magnetization for Fe23Y6; the calculated Curie temperature is 500 K [84Her]. 60Bea: B.J. Beaudry, J.F. Haefling, and A.H. Daane, Acta Crystallogr., 13, 743 (1960). 61Dom: R.F. Domagala, J.J. Rausch, and D.W. Levinson, Trans. ASM, 53, 139-155 ( 1961). 61Dwi: A.E. Dwight, Trans. ASM, 53, 479-500 (1961). 61Gsc: K.A. Gschneidner, Jr., Rare Earth Alloys, Van Nostrand Publishing, Amsterdam (1961). 66Bus: K.H.J. Buschow, J. Less-Common Met., 11, 204-208 (1966). 71Tay: K.N.R. Taylor and C.A. Poldy, J. Less-Common Met., 27, 255 (1972). 77Bus: K.H.J. Buschow, Rep. Prog. Phys., 40, 1179-1256 (1977). 79Bes: M.J. Besnus, J.M. Bouton, and R. Clad, Phys. Status Solidi (a), 53, 351- 354 (1979). 81Ten: M. Tenhover, J. Phys. F, Metal Phys., 11, 2697-2670 (1981). 82Kub: O. Kubaschewski, Iron-Binary Phase Diagrams, Springer-Verlag, New York, 106-107 (1982). 82Ten: M. Tenhover, B.M. Clemens, and P. Duwez, J. Phys. F, Met. Phys., 12, L167-L171 (1982). 84Bay: G. Bayer and W.E. Wallace, J. Phys. Chem., 88, 3220-3224 (1984). 84Her: J.F. Herbst and J.J. Croat, J. Appl. Phys., 55(8), 3023-3027 (1984). 86Chu: Y.C. Chuang, C.H. Wu, and Y.C. Chang, J. Less-Common Met., 118, 7-20 ( 1986). Submitted to the APD Program. Complete evaluation contains 1 figure, 4 tables, and 32 references. Special Points of the Fe-Y System

 




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