Фазовая диаграмма системы Cu-Ho

К оглавлению: Другие диаграммы (Others phase diargams)

Cu-Ho (Copper-Holmium) P.R. Subramanian and D.E. Laughlin Phase diagram information on the Cu-Ho system is limited. The assessed diagram is calculated and has been derived from thermodynamic considerations, as well as the systematics of Cu-lanthanide systems. [63Wun] investigated the solid solubility of Ho in (Cu) in the range 500 to 1000 C. They observed that the solid solubility did not show any appreciable temperature dependence in this range, and that the maximum solid solubility of Ho in Cu is ~0.02 at.% Ho (0.06 wt.% Ho) at the eutectic temperature. Studies on alloys containing ~4.1 at.% Ho (10 wt.% Ho) revealed the Cu-rich eutectic temperature to be 868 C, and the corresponding liquidus temperature to be 1025 C. [65Wun] redetermined the eutectic temperature in the Cu-rich region and found it to be 864 C. There is no other experimental phase diagram information on the Cu-Ho system. In the calculated diagram, the existence of Cu9Ho2 and Cu7Ho2 is proposed solely on the basis of the presence of similar phases in the Cu-Gd [83Car], Cu-Dy [82Fra], and Cu-Er [ 70Bus] systems. Also, there is a possibility that Cu7Ho exists. A similar phase is found inthe Cu-Dy system, but not in the Cu-Er system, and because Ho lies between Dy and Er in the lanthanide series, it is difficult to assess whether this phase will exist in the Cu-Ho system. Because no thermodynamic data are available for the Cu-Ho system, thermodynamic modeling of the liquid phase involved the assumptions that the liquid behaves like a subregular solution. The Cu-rich liquidus below 9.5 at.% Ho and the Ho-rich liquidus above 70 at.% Ho were calculated from thermodynamic data, and the remaining liquidus was estimated from systematics of Cu-lanthanide systems. The equilibrium temperatures of known Cu-Ho intermediate phases were obtained by interpolation of corresponding data for other known Cu-lanthanide systems. [79Mcg] prepared amorphous thin films with the composition Cu0.56Ho0.44 by sputtering from arc-melted specimens, and by thermal evaporation from Cu and Ho targets, followed by condensation on liquid nitrogen-cooled sapphire substrates. The resultant films were 500 to 1000 nm thick. 61Dwi: A.E. Dwight, Trans. ASM, 53, 479-500 (1961). 63Sto: A.R. Storm and K.E. Benson, Acta Crystallogr., 16, 701-702 (1963). 63Wun: W.J. Wunderlin, B.J. Beaudry, and A.H. Daane, Trans. AIME, 227, 1302- 1305 (1963). 64Cha: C.C. Chao, H.L. Luo, and P. Duwez, J. Appl. Phys., 35, 257-258 (1964). 65Ian: A. Iandelli and A. Palenzona, J. Less-Common Met., 9, 1-6 (1965). 65Wun: W.J. Wunderlin, B.J. Beaudry, and A.H. Daane, Trans. AIME, 223, 436 ( 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). 79Mcg: T.R. McGuire and R.J. Gambino, J. Appl. Phys., 50(11), 7653-7655 (1979). 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). 86Sme: Z. Smetana, V. Sima, and B. Lebech, J. Magn. Magn. Mater., 59, 145-152 ( 1986). Published in Bull. Alloy Phase Diagrams, 9(3a), Jun 1988. Complete evaluation contains 1 figure, 5 tables, and 18 references. Special Points of the Cu-Ho System