Фазовая диаграмма системы Be-Zr

К оглавлению: Другие диаграммы (Others phase diargams)

Be-Zr (Beryllium-Zirconium) H. Okamoto, L.E. Tanner, and J.P. Abriata The assessed phase diagram for the Be-Zr system is based on the experimental data of [36Mis], [50Hau], [59Pai], [60Bed], [60Eme], [60Sto], and [65Bea] and was obtained by thermodynamic modeling. The thermodynamic functions for the solid solution phases are adopted from [79Kau]. The coefficients of a regular solution model for the liquid phase have been determined from the assessed L = Be2Zr + (bZr) eutectic point, using recently reassessed values for the enthalpies of transformation of the pure elements [83Cha] and setting the melting point for Be13Zr at 1800 C. In addition to the terminal solid solutions, (bBe), (aBe), (bZr), and (aZr), the assessed diagram includes four intermediate phases, Be13Zr, Be17Zr2, Be5Zr, and Be2Zr, each having a limited homogeneity range. Phase boundaries drawn in the assessed diagram are based on the present thermodynamic model. This diagram must be regarded as tentative, especially along the liquidus boundaries, because experimental melting data are limited. Data regarding the other boundaries and the compositions of the intermediate phases come from a variety of sources, and earlier reports tend to exhibit significant inconsistencies regarding existing phases and reaction temperatures.[60Gel] indicated that the L = (bBe) + Be13Zr eutectic temperature is 1275 C. This temperature is probably lower than the actual value by several degrees, because the observed melting point of Be (~1280 C) is lower than the assessed value (1289 с 5 C). The (bBe) = (aBe) + Be13Zr eutectoid temperature is 1260 C [60Gel], which also is probably lower than the actual value. No solubility of Zr in (Be) was detected from lattice parameter determinations as a function of composition [50Kau, 62Amo]. However, metallographic evidence indicated that the solubility limit was <0.03 at.% Zr [60Eme] and 0.01 at.% Zr [61Hin]. An estimate of the maximum solubility of Zr in (bBe) from the present thermodynamic model is as small as ~0.001 at.% Zr at 1288.5 C (the calculated eutectic temperature). The solubility limit of Be in Zr (probably bZr) is 5 at.% [50And]. A 0.77 at.% Be alloy homogenized at 850 C was two phase [50And]. The solubility limit of Be is less than 3.0 at.% in (bZr) at 965 C and much less than 1.0 at.% in ( aZr) [60Eme]. These observations are in qualitative agreement with the assessed phase diagram. The (bZr) = (aZr) transition temperature in alloys is 800 C [60Eme], in agreement with the present thermodynamic calculation. Be17Zr shows high oxidation resistance, even at 1650 C [61CEN]. No other reports are found on an alloy of this composition, and therefore, it is not shown in the assessed diagram. Be-Zr alloys with 55 to 70 at.% Zr can be made amorphous by means of rapid liquid quenching at rates exceeding 105 C/s [77Has, 79Tan]. A CrB-type metastable phase, BeZr, was found by [79Tan] in liquid quenched samples but not in the course of crystallization of glasses. The solubility limit of Be in (bZr) extends to about 10 at.% by liquid quenching. Acicular martensite (a›) forms from primary (bZr) during cooling, in the composition range from 95 to 100 at.% Zr [79Tan]. 36Mis: L. Misch, Metallwirtschaft, 15(6), 163-166 (1936) in German. 49Bae: N.C. Baenziger and R.E. Rundle, Acta Crystallogr., 2(4), 258 (1949). 50And: C.T. Anderson, E.T. Hayes, A.H. Roberson, and W.J. Kroll, U.S. Bureau of Mines, Rept. Invest. 4658, 48 p (1950). 50Hau: H.H. Hausner and H.S. Kalish, Trans. Metall. AIME, 188(1), 59-66 (1950); Discussion in Trans. Metall. AIME, 188(11), 1369-1371 (1950). 50Kau: A.R. Kaufmann, P. Gordon, and D.W. Lillie, Trans. ASM, 42, 785-844 ( 1950). 54Nie: J.W. Nielsen and N.C. Baenziger, Acta Crystallogr., 7(1), 132-133 (1954) . 59Chu: W. Chubb and R.F. Dickerson, U.S. At. Energy Comm. BMI-1327, 18 p (1959) . 59Pai: R.M. Paine, A.J. Stonehouse, and W.W. Beaver, WADC Tech. Rep., Part I, 266 p (1959). 59Zal: A. Zalkin, R.G. Bedford, and D.E. Sands, Acta Crystallogr., 12(9), 700 ( 1959). 60Bed: R.G. Bedford, U.S. At. Energy Comm. UCRL-5991-T, 7 p (1960). 60Eme: V.S. Emel'yanov, Yu.G. Godin, and A.I. Evstyukhin, At. Energy (USSR), 9, 33-38 (1960) in Russian; TR: Sov. J. At. Energy, 9, 528-533 (1961). 60Gel: S.H. Gelles and J.J. Pickett, U.S. At. Energy Comm. NMI-1218, 44 p ( 1960). 60Sto: A.J. Stonehouse, R.M. Paine, and W.W. Beaver, in Mechanical Properties of Intermetallic Compounds, J.H. Westbrook, Ed., John Wiley & Sons, New York, 297-319 (1960). 60Zal: A. Zalkin and D.E. Sands, U.S. At. Energy Comm. UCRL-5988-T, 6 p, May 24 (1960). 61CEN: Chem. Eng. News, 39(46), 65-66 (1961). 61Hin: E.D. Hindle and G.F. Slattery, Institute of Metals Conference on Metallurgy of Beryllium, London, Preprint No. 58, 8 p (1961); Inst. Metals, Monograph Rep. Ser. No. 28, Institute of Metals, London, 651-664 (1963). 61Rud: E. Rudy, F. Benesovsky, H. Nowotny, and L.E. Toth, Monatsh. Chem., 92, 692-700 (1961). 61Zal: A. Zalkin, D.E. Sands, R.G. Bedford, and O.H. Krikorian, Acta Crystallogr., 14(1), 63-65 (1961). 62Amo: V.M. Amonenko, V.Ye. Ivanov, G.F. Tikhinskiy, and V.A. Finkel, Fiz. Met. Metalloved., 14(6), 852-857 (1962) in Russian; TR: Phys. Met. Metallogr., 14( 6), 47-51 (1962). 65Bea: W.W. Beaver, A.J. Stonehouse, and R.M. Paine, Plansee Proceedings, 1964, Metals for the Space Age, Metallwerk Plansee AG, Reutte/Tirol, 682-700 (1965). 75Stu: M. Stumke and G. Petzow, Z. Metallkd., 66(5), 292-297 (1975) in German. 77Has: R. Hasegawa and L.E. Tanner, Phys. Rev. B, 16(9), 3925-3928 (1977). 79Kau: L. Kaufman and L.E. Tanner, Calphad, 3(2), 91-107 (1979). 79Tan: L.E. Tanner and R. Ray, Acta Metall., 27, 1717 (1979). 83Cha: M.W. Chase, Bull. Alloy Phase Diagrams, 4(1), 123-124 (1983). 84Col: D.M. Collins and T.J. Delord, Acta Crystallogr. C, 40(9), 1497-1498 ( 1984). Published in Phase Diagrams of Binary Beryllium Alloys, 1987. Complete evaluation contains 3 figures, 6 tables, and 40 references. 1