Фазовая диаграмма системы Gd-Mg

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Gd-Mg (Gadolinium-Magnesium) A.A. Nayeb-Hashemi and J.B. Clark The assessed phase diagram for the Mg-Gd system is taken from [86Man], with minor changes, and from [77Rok], with review of the experimental data of [ 65Jos]. It consists of: (1) the liquid, L; (2) the terminal (Mg) solid solution, (3) the terminal (aGd) and (bGd) solid solutions; and (4) four intermetallic compounds (Mg5Gd, Mg3Gd, Mg2Gd, and MgGd). The (Mg) solidus reported by [77Rok] is not highly accurate and needs to be confirmed. [86Man] showed the maximum solid solubility of Mg in (bGd) as 36.6 at.% Mg (63. 4 at.% Gd) at 868 C. However, they did not show enough experimental points in their Mg-Gd phase diagram to justify showing the (aGd)/(aGd) + (bGd) boundary and the (bGd)/(bGd) + MgGd boundary as solid lines. These boundaries are shown as dashed lines in the assessed diagram. In the assessed diagram, the maximum solid solubility of Gd in (Mg) at the eutectic temperature (548 с 2 C) is shown as 4.53 at.% Gd, and the maximum solid solubility of Mn in (aGd) at the eutectoid temperature (700 с 2 C) is shown as >14.1 at.% Mg (<85.9 at.% Gd). [51Gau], [52Gau], [53Gau], and [54Gau] investigated the magnetic properties of Mg-Gd alloys and reported that alloys in the composition range 0 to 22.3 at.% Gd are "purely" paramagnetic, and those in the composition range 26.5 to 100 at.% Gd show marked ferromagnetic properties at low temperatures. The transition from purely paramagnetic alloys to ferromagnetic alloys was reported to occur at Mg3Gd (25 at.% Gd) stoichiometry. [52Gau] reported that alloys of 28.44 to 44.80 at.% Gd have a single Curie point at 102 K (see also [ 61Gsc]). [73Bus], [74Bus], [76Bus1], and [75Ale] investigated the magnetic properties of MgGd. According to [73Bus], the Curie temperature, TC, of MgGd is 120 K. The TC was reported as 121 K [74Bus] and 119 K [75Ale]. However, [75Ale] reported that MgGd has a non-colinear magnetic structure with a ferromagnetic component. The spontaneous magnetization reaches 4.5 mB at 4.2 K (see also [ 80Pie]). [78Bus1] studied the magnetic properties of Mg2RE compounds in the temperature range 1.5 to 300 K and the magnetic field of up to 18 kOe. According to [ 78Bus1], most of the Mg2RE compounds order ferromagnetically at temperatures " well below 100 K," except for Mg2La, Mg2Yb, and Mg2Y, which show Pauli paramagnetism; Mg2Sm and Mg2Eu order antiferromagnetically. The TC of Mg2Gd was found to be 81 K [78Bus1]. [76Bus2] (see also [78Bus2]) investigated the magnetic properties of Mg3RE compounds in the temperature range 4 to 300 K, with a magnetic field of up to 18 kOe. Mg3Gd and Mg3Tb were found to order ferromagnetically. The TC for Mg3Gd is 117 K. [79Pie] (see also [78Mor]) investigated the specific heat of MgGd and the contribution of its magnetic behavior to its specific heat. [79Pie] reported two anomalies in the plot of specific heat vs temperature, one at the TC (119 с 4 K) and another at the ferromagnetic canted structure transition (Tcant = 96 с 2 K). The ferromagnetic canted state transition was reported as 85 с 5 K from neutron diffraction of a different sample. 51Gau: F. Gaume-Mahn, Compt. Rend., 232, 1815-1816 (1951) in French. 52Gau: F. Gaume-Mahn, Compt. Rend., 235, 352-354 (1952) in French. 53Gau: F. Gaume-Mahn, Compt. Rend., 237, 702-704 (1953) in French. 54Gau: F. Gaume-Mahn, Bull. Soc. Chim. Fr., 21, 569-575 (1954) in French. 60Ian: A. Iandelli, Atti. Accad. Nazl. Lincei Rend., 29, 62-69 (1960) in Italian. 61Gsc: K.A. Gschneidner, Jr., Rare Earth Alloys, Van Nostrand, Princeton, NJ ( 1961). 61Sav: E.M. Savitskii, V.F. Terekhova, J.V. Burov, and J.A. Morkova, Zh. Neorg. Khim., 6, 1734-1736 (1961) in Russian; TR: Russ. J. Inorg. Chem., 6(7), 885- 886 (1961). 63Kri: P.I. Kripyakevich, V.F. Terekhova, O.S. Zarechnyuk, and I.V. Burov, Kristallografiya, 8, 268 (1963) in Russian; TR: Russ. Crystallogr., 8, 203 ( 1963). 64Kri: P.I. Kripyakevich and V.I. Evdokimenko, Problems of the Theory and Application of Rare Earth Metals, E. Savitskii and V.F. Terekhova, Ed., Nauka, Moscow, 191-194 (1964). 64Mil: A.E. Miller and A.H. Daane, Trans. AIME, 230, 568-572 (1964). 65Ian: A. Iandelli and A. Palenzona, J. Less-Common Met., 9, 1-6 (1965). 65Jos: R.R. Joseph and K.A. Gschneidner, Jr., Trans. AIME, 233, 2063-2069 ( 1965). 66Cha: C.C. Chao and P. Duwez, J. Appl. Phys., 37(7), 2631-2632 (1966). 69Kri: P.I. Kripyakevich and V.I. Evdokimenko, Visn. Lviv. Derzh. Univ., Ser. Khim., (11), 3-7 (1969) in Russian. 73Bus: K.H.J. Buschow, J. Less-Common Met., 33, 239-244 (1973). 74Bus: K.H.J. Buschow and A. Oppelt, J. Phys. F, Met. Phys., 4, 1246-1255 ( 1974). 75Ale: R. Aleonard, P. Morin, J. Pierre, and D. Schmitt, Solid State Commun., 17, 599-603 (1975). 76Bus1: K.H.J. Buschow and C.J. Schinkel, Solid State Commun., 18, 609-612 ( 1976). 76Bus2: K.H.J. Buschow, J. Less-Common Met., 44, 301-306 (1976). 77Rok: L.L. Rokhlin and N.I. Nikitina, Izv. V.U.Z. Tsvetn. Metall., (1), 167- 168 (1977) in Russian; TR: Sov. Non-Ferrous Met. Res., 5(1), 40 (1977). 78Bea: B.J. Beaudry and K.A. Gschneidner, Jr., Handbook on the Physics and Chemistry of Rare Earths, Vol. 1-Metals, K.A. Gschneidner, Jr. and L. Eyring, Ed., North-Holland Publishing Co., Amsterdam, 173-232 (1978). 78Bus1: K.H.J. Buschow, R.C. Sherwood, and F.S.L. Hsu, J. Appl. Phys., 49(3), 1510-1512 (1978). 78Bus2: K.H.J. Buschow, G. Will, and M.O. Bargouth, J. Phys. C, Solid State Phys., 11, 2405-2413 (1978). 78Mor: P. Morin, J. Pierre, D. Schmitt, and D. Givord, Phys. Lett. A, 65, 156- 158 (1978). 79Pie: M. Pierre, A. Combarieu, and R. Lagnier, J. Phys. F, Met. Phys., 9(7), 1271-1282 (1979). 80Pie: J. Pierre, A.P. Murani, and R.M. Galera, J. Phys. F, Met. Phys., 11, 679-680 (1980). 86For: M.L. Fornasini, P. Manfrinetti, and K.A. Gschneidner, Jr., Acta Crystallogr., C42, 138-141 (1986). 86Man: P. Manfrinetti and K.A. Gschneidner, Jr., J. Less-Common Met., 123, 267- 275 (1986). Published in Phase Diagrams of Binary Magnesium Alloys, 1988. Complete evaluation contains 1 figure, 7 tables, and 36 references. Special Points of the Mg-Gd System