Фазовая диаграмма системы Be-Fe

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Be-Fe (Beryllium-Iron) H. Okamoto and L.E. Tanner The assessed equilibrium diagram for the Be-Fe system is based primarily on review of the experimental work of [16Oes], [29Wev], [48Gor], [48Tei], [59Gel] , [60Gel], [62Don], [63Heu], [65Ham], [75Ko], [78Myc], and [82Jon] and represents an update of the diagram of [79Ald], using more recent data provided by [75Ko] and [82Jon]. The former confirmed the (aFe) solvus trend observed by [63Heu]. The assessed diagram has been obtained by thermodynamic modeling. Three intermediate phases exist in the Be-Fe system-e, d, and z. The e and d phases in the present evaluation have been adopted from [82Jon]. The former corresponds to the e Hume-Rothery phases. The MgCu2-type d phase, which was called e by [49Tei], [Hansen], and [Elliott], has the same structure and a nearly identical lattice parameter as the d phase in the Be-Cu system. The nomenclature of the MnZn2-type z phase used in this evaluation has been adopted from [Hultgren,B]. The z phase in the Be-Co diagram has a similar composition range, although its structure is different. The present evaluators reserve g for the Ni5Zn21-type phases in the Be-Co and Be-Ni phase diagrams. Because [32Slo] found double thermal arrests in Be, the presence of an allotropic transformation in Be had been disputed when [48Tei] investigated the Be-Fe phase diagram. [48Tei] explained the complicated arrest behaviors observed in the composition range between 0 and 8 at.% Fe as resulting from impurities present in the specimens rather than as the effect of an allotropic transformation of Be. Subsequently, [60Gel] clarified the phase relationship between (bBe) and (aBe), suggesting that the specimens used by [48Tei] were of higher purity than previously thought. The (bBe) = (aBe) + d eutectoid transformation temperature is 1205 C [82Jon]. The maximum solid solubility of Fe in (aBe) is about 0.9 at.% at 1205 C. Alloys with 2.3 and 5 at.% Fe are not superconducting, at least above 0.45 K [ 67Ols]. The homogeneity range of e has not been clarified. [48Tei] estimated the maximum transition temperature of e as ~1175 or 1188 C from the trend of the d/[e + d] boundary extrapolated to 8 at.% Fe. The phase boundaries of this phase in the assessed diagram are tentative. The d phase covers the composition range form ~7 to 18 at.% Fe. The L + z = d peritectic temperature was determined by [48Gor] as 1375 C from an arrest point in a 20 at.% Fe alloy and has been accepted in all subsequent reviews. [ 48Gor] reported the point at 20 at.% Fe and 1355 C as the [L + d]/d boundary. However, according to the assessed diagram, this is not the case. Therefore, the peritectic temperature of 1375 C may have to be reinvestigated. X-ray investigations by [48Tei] on specimens quenched from 1200 and 1025 C and on specimens annealed at 530 C for a month suggested that the Be-rich phase boundary of the z phase is about 21 at.% Fe. The congruent melting point is 1463 C at 28 at.% Fe [82Jon]. The solidus boundary of (aFe) is not well defined, because the limited experimental data available are outdated. The two-phase field between (gFe) and (aFe) was not discerned experimentally. The assessed diagram is based on the present thermodynamic modeling. Because the solid solubility of Be in (aFe) decreases significantly at low temperatures from the value near the eutectic temperature, the age hardening process of this phase was studied extensively. The various investigators agreed that several intermediate stages exist before the final equilibrium condition is attained, but disagreed about the details of the phases. The initial stage of age hardening is a composition modulation of the homogeneous bcc (aFe) structure [84Mil1]. Eventually, the modulations develop into metastable precipitates with structures related to the matrix. It is generally agreed that the modulation gives rise to two phases, (aFe) depleted in Be and CsCl-type metastable BeFe (b), at least at low temperatures. Finally, the stable precipitate, Be2Fe, forms. Therefore, metastable phase diagrams vary depending on the stage of the precipitation process they represent. [78Tya] reported that the A2 phase shows a miscibility gap in the metastable state. The A2/B2 transition is second order at high temperatures and a metastable miscibility gap exists in B2 [84Mil2]. Only [68Nak] showed the BiF3- type (D03) BeFe3 in the metastable phase diagram. [66Dav] found the D03 phase in an ordered B2 matrix of 27 at.% Be. [65Bol] obtained pure BeFe3 with the long-range order parameter better than 0.9. BeFe3 appears to be a transient phase. The Curie temperature of aFe is 770 C [82Swa]. The change of magnetic moment in (aFe) is 2.216 - 2.01(XBe)) mB [69Her]. [35Mis1] found that Be2Fe (z) is ferromagnetic with a magnetic transition temperature at 521 to 524 C. The change of magnetic moment in z is 3.07 - 3.65 (1 - XBe) mB [69Her]. The d phase also becomes ferromagnetic at liquid air temperature [35Mis]. The Curie temperature is 75 K [67Her]. The Curie temperature of a 33.3 at.% Fe alloy is 643 C [51Mey]. 16Oes: G. Oesterheld, Z. Anorg. Allg. Chem., 97, 6-40 (1916) in German. 29Wev: F. Wever and A. Muller, Mitt. Kaiser-Wilhelm-Inst. Eisenforsch. Dusseldorf, 11, 193-223 (1929) in German. 35Mis: L. Misch, Z. Phys. Chem. B, 29, 42-58 (1935) in German. 37Gae: I.S. Gaev and P.S. Sokolov, Metallurg, 12(4), 42-48 (1937) in Russian. 48Gor: P. Gordon, Manhattan Project, unpublished data shown in [48Tei]. 48Tei: R.J. Teitel, "The Beryllium-Iron System," U.S. At. Energy Comm., Publ. AECD-2251 (1948). 49Tei: R.J. Teitel and M. Cohen, Trans. Metall. AIME, 185(4), 285-296 (1949); discussions: Trans. Metall. AIME, 188(8), 1028-1029 (1950). 51Mey: A.J.P. Meyer and P. Taglang, Compt. Rend., 232, 1545-1546 (1951) in French. 57Bat: F.W. von Batchelder and R.F. Raeuchle, Acta Crystallogr., 10, 648-649 ( 1957). 59Gel: S.H. Gelles, R.E. Ogilvie, and A.R. Kaufmann, Trans. Metall. AIME, 215( 8), 695-702 (1959). 60Gel: S.H. Gelles and J.J. Pickett, U.S. At. Energy Comm. NMI-1218, 44 p ( 1960). 61Oht: K. Ohta and Y. Kobayashi, Kobayashi Rigaku Kenkyusho Hokoku, 11(3), 61- 64 (1961) in Japanese. 62Don: G. Donze, R. Le Hazif, F. Maurice, G. Dutilloy, and Y. Adda, Compt. Rend., 254, 2328-2330 (1962) in French. 62Roo: H.P. Rooksby, J. Nucl. Mater., 7(2), 205-211 (1962). 63Heu: U. Heubner, Arch. Eisenhuttenwes., 34, 547-552 (1963) in German. 65Bol: G.F. Bolling and R.H. Richman, Acta Metall., 13(7), 709-757 (1965). 65Ham: M.L. Hammond, A.T. Davinroy, and M.I. Jacobson, Tech. Rept., AFML-TR-65- 223 (AD 468484), 77 p (1965). 66Dav: R.G. Davies and R.H. Richman, Trans. Metall. AIME, 236(11), 1551-1557 ( 1966). 67Her: A. Herr and A.J.P. Meyer, Compt. Rend. B, 265, 1165-1168 (1967) in French. 67Ols: C.E. Olsen, B.T. Matthias, and H.H. Hill, Z. Phys., 200, 7-12 (1967). 68Dzh: M.V. Dzhibuti and Yu.D. Tyapkin, Kristallografiya., 13(2), 307-310 ( 1968) in Russian; TR: Sov. Phys. Crystallogr., 13(2), 240-244 (1968). 70Joh: Q. Johnson, G.S. Smith, O.H. Krikorian, and D.E. Sands, Acta Crystallogr. B, 26(2), 109-113 (1970). 75Ko: M. Ko and T. Nishizawa, Trans. Jpn. Inst. Met., 16(6), 369-371 (1975). 78Mye: S.M. Myers and J.E. Smugeresky, Metall. Trans. A, 9(12), 1789-1794 ( 1978). 78Tya: Yu.D. Tyapkin, T.V. Yevtushenko, and N.T. Travina, Fiz. Met. Metalloved. , 45(2), 315-326 (1978) in Russian; TR: Phys. Met. Metall., 45(2), 72-82 (1978) . 79Ald: F. Aldinger and G. Petzow, in Beryllium Science and Technology, D. Webster and G.J. London, Ed., 1, 235-305 (1979). 82Jon: S. Jonsson, K. Kaltenbach, and G. Petzow, Z. Metallkd., 73(8), 534-539 ( 1982). 84Mil1: M.K. Miller, S.S. Brenner, M.G. Burke, and W.A. Soffa, Scr. Metall., 18, 111-116 (1984). 84Mil2: M.K. Miller, M.G. Burke, S.S. Brenner, W.A. Soffa, K.B. Alexander, and D.E. Laughlin, Scr. Metall., 18, 285-290 (1984). Published in Bull. Alloy Phase Diagrams, 9(4), Aug 1988, and Phase Diagrams of Binary Beryllium Alloys, 1987. Complete evaluation contains 8 figures, 10 tables, and 80 references. Special Points of the Be-Fe System