Фазовая диаграмма системы Cu-Er

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Cu-Er (Copper-Erbium) P.R. Subramanian and D.E. Laughlin The assessed phase diagram for the Cu-Er system is based on the experimental data of [70Bus]. Minor modifications have been made in the liquidus between Cu2Er and CuEr, so that the slope of the liquidus at the congruent melting point of Cu2Er conforms to the Gibbs-Konovalov criterion [81Goo]. This involved a shift in the estimated value of the Cu2Er-CuEr eutectic composition from 40 at.% Er (estimated by [70Bus]) to 38.5 at.% Er. The Er-rich liquidus above 75 at.% Er was shown with dashed lines in the diagram of [70Bus], and is indicated in the same manner in the assessed diagram, where the melting point for pure Er has been raised to 1529 C to conform to the accepted value. [70Bus] observed the peritectic formation of Cu5Er and the congruent formation of Cu2Er and CuEr. Moreover, thermal analysis indicated the existence of two additional phases occurring near 20 at.% Er, which [70Bus] designated as CuxEr and CuyEr, respectively. These phases are very close to the stoichiometries of Cu7RE2 (22.2 at.% RE) and Cu9RE2 (18.2 at.% RE), respectively, which have been observed to form for RE = Gd [83Car], RE = Dy [82Fra], and RE = Yb [71Ian] systems. [70Bus] reported that the phase lower in Er forms congruently at 1010 C, and the other phase forms peritectically at 940 C. Again, this pattern is consistent with the melting types reported for Cu9RE2 (congruent) and Cu7RE2 ( peritectic), where RE = Gd, Dy, and Yb. As such, the phases CuxEr and CuyEr have been tentatively assigned the stoichiometries Cu7Er2 and Cu9Er2, respectively. Mutual solid solubilities were reported to be negligible, because elemental lattice parameters did not change significantly on alloying. [70Bus] inferred that CuEr decomposes partially into Cu2Er and (Er) at lower temperatures. According to [70Bus], this decomposition is expected to be sluggish because of the large concentration difference between Cu2Er and (Er). Amorphous thin films with the composition Cu0.49Er0.51 were prepared by [79Mcg] by sputtering from arc-melted specimens, and by thermal evaporation from Cu and Er targets, followed by condensation on liquid nitrogen-cooled sapphire substrates. The resultant films were 500 to 1000 nm thick. 59Dwi: A.E. Dwight, U.S. At. Energy Com. Rep. ANL-6099, 94-96 (1959); as quoted in [Elliott]. 63Sto: A.R. Storm and K.E. Benson, Acta Crystallogr., 16, 701-702 (1963). 65Ian: A. Iandelli and A. Palenzona, J. Less-Common Met., 9, 1-6 (1965). 69Bus: K.H.J. Buschow, A.S. van der Goot, and J. Birkhan, J. Less-Common Met., 19, 433-436 (1969). 70Bus: K.H.J. Buschow, Philips J. Res., 25, 227-230 (1970). 71Ian: A. Iandelli and A. Palenzona, J. Less-Common Met., 25, 333-335 (1971). 79Mcg: T.R. McGuire and R.J. Gambino, J. Appl. Phys., 50(11), 7653-7655 (1979). 81Goo: D.A. Goodman, J.W. Cahn, and L.H. Bennett, Bull. Alloy Phase Diagrams., 2(1), 29-34 (1981). 82Fra: E. Franceschi, J. Less-Common Met., 87, 249-256 (1982). 83Car: M.M. Carnasciali, S. Cirafici, and E. Franceschi, J. Less-Common Met., 92, 143-147 (1983). Published in Bull. Alloy Phase Diagrams, 9(3a), Jun 1988. Complete evaluation contains 2 figures, 6 tables, and 17 references. Special Points of the Cu-Er System