Фазовая диаграмма системы Ge-Ni

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Ge-Ni (Germanium-Nickel) A. Nash and P. Nash The Ni-Ge system is rather complex, with many invariant reactions, and it cannot be considered well established, particularly from 20 to 50 at.% Ge. The phases bNi3Ge, gNi3Ge, dNi5Ge2, eNi5Ge3, and NiGe are well established. The existence of Ni19Ge12, Ni2Ge, and e› (low-temperature Ni5Ge3) has only been reported by [71Ell]. The assessed phase diagram is based primarily on the work of [40Rut], [71Ell], and [80Day], with the portion between 35 and 40 at.% Ge below 400 C based only on the data of [71Ell]. The maximum solid solubility of Ge in (Ni) is 16 at.% at 1124 C. The solubility of Ni in (Ge) is greatest at 875 C (1.8 x 10-5 at.% Ni) and decreases to 4.5 x 10-7 at.% Ni at 700 C [60Tru]. The b phase melts congruently at 1132 C, and the (Ni) liquidus therefore drops to a eutectic, L = (Ni) + b, at 1124 C [80Day]. g forms peritectically from the liquid and b. The peritectic formation of d has also been established as L + g = d [80Day]. Because e is congruently melting, a eutectic occurs, L = d + e. The peritectic formation of NiGe occurs at 850 C. bNi3Ge has a homogeneity range of 22.5 to 25 at.% Ge over the complete temperature range. gNi3Ge is formed at 1118 C by a peritectic reaction, L + bNi3Ge = gNi3Ge, and is stable down to 1082 C at a composition of 25.6 at.% Ge. dNi5Ge2 is formed at 1102 C by a peritectic reaction of gNi3Ge, with a melt composition of 28.9 at.% Ge, giving a d composition of 28 at.% Ge. dNi5Ge2 is also formed from the eutectoid reaction of gNi3Ge at 1082 C in the composition range 25 to 28 at.% Ge. However, the d phase decomposes by a eutectoid decomposition at 1045 C, yielding bNi3Ge + eNi5Ge3 in the composition range 25 to 33.6 at.% Ge. Ni2Ge forms by a peritectoid reaction at 506 C. The homogeneity range has not been determined, but is narrow and centered around 33.5 at.% Ge [71Ell]. [80Day] found the e phase to be Ni5Ge3, with a maximum homogeneity range of 33. 8 to 43.2 at.% Ge at 850 C. However, at 1000 C, this range is smaller (33.6 to 42.2 at.% Ge) and is even more restricted (34.2 to 40.9 at.% Ge) at 700 C. The low-temperature form of the e phase, e›Ni5Ge3, forms from a eutectoid reaction at 290 C [71Ell]. The reaction product compositions are approximately 33.5 and 37 at.% Ge for Ni2Ge and e›Ni5Ge3, respectively. The homogeneity range of e› is narrow, although not clearly determined. Ni19Ge12 forms from the eutectoid decomposition of Ni3Ge2 at 515 C. The homogeneity range has not been determined. Eutectoid decomposition of the e phase at 394 C yields e›Ni5Ge3 and Ni19Ge12, whereas the decomposition of Ni19Ge12 at 382 C yields e›Ni5Ge3 and NiGe. [77Kor] prepared films of Ni0.625Ge0.375 alloy in amorphous, crystalline, and mixed states by condensation. The amorphous structure was laminated and consisted of nonuniform admixtures throughout the film thickness. The amorphous-crystalline transition temperature was dependent on the film thickness. [74Pol] carried out X-ray analysis of thin films of Ni containing 9.4 to 76.5 at.% Ge obtained on rapid quenching at ~108 C/s. The solid solubility was extended up to 21.3 at.% Ge. In alloys containing 23.9 at.% Ge, a metastable rhombic phase was formed. After heating to 400 C, this alloy transformed to an ordered b phase. 40Rut: K. Ruttewit and G. Masing, Z. Metallkd., 32, 51-61 (1940) in German. 60Tru: F.A. Trumbore, Bell Sys. Tech. J., 39, 205-233 (1960). 63Lec: P. Lecocq., Ann. Chim., 8, 85-116 (1963). 71Ell: M. Ellner, T. Goedecke, and K. Schubert, J. Less-Common Met., 24, 23-40 (1971). 74Pol: A.F. Polesya and L.S. Slipchenko, Izv. Akad. Nauk SSSR, (2), 239 (1974). 77Kor: T.S. Korsunskaya, Y.V. Kurdyautsev, and I.V. Lezhnenko, Ukr. Fiz. Zh., 22(4), 642-645 (1977) in Russian. 80Day: A. Dayer and P. Feschotte, J. Less-Common Met., 72, 51-70 (1980). Published in Phase Diagrams of Binary Nickel Alloys, 1991, and Bull. Alloy Phase Diagrams, 8(3), Jun 1987. Complete evaluation contains 5 figures, 6 tables, and 48 references. Special Points of the Ni-Ge System