Фазовая диаграмма системы Cr-Ru

К оглавлению: Другие диаграммы (Others phase diargams)


Cr-Ru (Chromium-Ruthenium) M. Venkatraman and J.P. Neumann The assessed phase diagram for the Cr-Ru system is based on review of the work of [55Rau], [56Gre], [61Sav], [64Shu], [79Wop], and [81Wat]. It is similar to the diagram of [Shunk] and is characterized by extensive homogeneity ranges of the (Cr) and (Ru) terminal solid solutions and the presence of two intermediate phases. Cr3Ru has a narrow homogeneity range; it is shown as a line compound at 25 at.% Ru, but its homogeneity range may extend с2 at.% Ru from the stoichiometric composition. It is stable from approximately 750 to 1000 C [79Wop]. The reported existence of a third phase at 20 at.% Ru is questionable. The s phase has a relatively narrow homogeneity range, extending from 32 с 2 to 36 с 2 at.% Ru. This phase forms peritectoidally slightly below the eutectic temperature at 1580 C [64Shu]. It decomposes eutectoidally at ~800 C [79Wop]. The accepted melting points of Cr and Ru are 1863 and 2334 C, respectively, based on the IPTS-68. The uncertainty in the location of the phase boundaries of the solvus curves of the (Cr) and (Ru) solid solutions is estimated to be с3 at.% Ru. Addition of Ru increases the N‚el temperature of pure Cr (311.5 K) to a maximum of ~550 K at ~5 at.% Ru. A further increase in the Ru content to ~15 at.% Ru lowers the N‚el temperature to ~273 K [64Boo]. The two intermediate phases, Cr3Ru and Cr2Ru (s), as well as the (Ru) solid solution, are superconducting. The transition temperatures of Cr3Ru and Cr2Ru are 3.3 and 2.0 K, respectively. In the (Ru) solid solution, the addition of Cr lowers the transition temperature of pure Ru (0.5 K) initially to less than 0.3 K in the region from 20 to 30 at.% Cr. A further increase in the Cr concentration raises the transition temperature to 1.65 K at 50 at.% Cr. 55Rau: E. Raub and W. Mahler, Z. Metallkd., 46, 210-215 (1955) in German. 56Gre: P. Greenfield and P.A. Beck, Trans. AIME, 206, 265-276 (1956). 61Sav: E.M. Savitskii, V.F. Terekhova, and N.A. Birun, Russ. J. Inorg. Chem., 6(8), 1002-1003 (1961). 64Boo: J.G. Booth, Phys. Status Solidi, 7, K157-K160 (1964). 64Shu: A.K. Shurin and G.P. Dmitrieva, Sb. Nauchn. Rab. Inst. Metallofiz. Akad. Nauk Ukr. SSR, (18), 170-174 (1964) in Russian. 79Wop: W. Wopersnow and Ch.J. Raub, Metall (Berlin), 33(12), 1261-1265 (1979) in German. 81Wat: R.M. Waterstrat, J. Less-Common Met., 80, P31-P36 (1981). Published in Bull. Alloy Phase Diagrams, 8(2), Apr 1987. Complete evaluation contains 1 figure, 1 table, and 20 references. 1