Фазовая диаграмма системы Cr-Cu

К оглавлению: Другие диаграммы (Others phase diargams)


Cr-Cu (Chromium-Copper) D.J. Chakrabarti and D.E. Laughlin The equilibrium phases of the Cu-Cr system are (1) the liquid, L; (2) the fcc solid solution, (Cu), with maximum solubility of approximately 0.89 at.% Cr at 1077 C; and (3) the bcc solid solution, (Cr), with negligible solubility of Cu below the eutectic temperature (1077 C). The assessed phase diagram is of the eutectic type, with a flat liquidus ( similar to Cu-Nb) and complete miscibility in the liquid state. Calculations based on the experimental phase diagram and thermodynamic results confirm that the miscibility gap in the liquid lies immediately below the equilibrium liquidus. The assessed diagram is based primarily on the work of [23Sie], [ 57Doi1], [77Kuz], and [82Tim]. The experimentally determined phase diagram of the Cu-Cr system has been at marked variance at the liquidus with the calculated one (based on thermodynamic modeling of the phase diagram data [77Kuz]) and with the measured (thermodynamic) activity results [82Tim]. The Cu-rich (Cu) solid solution alloys are age hardenable with minimal sacrifice of electrical conductivity [54Kos]. The precipitates formed at nearly pure Cu. They increase the recrystallization temperature, refine the grain size, and improve the high-temperature strength considerably [57Doi2]. [75Nag] reported the absence of a maximum aging temperature, above which reversion could not be observed. The absence of any metastable solvus and hence the absence of any metastable phase was inferred. Long aging times were used to increase the amount of precipitates formed. To detect reversion of metastable phases, a short aging time appears essential. Step-annealing involving isothermal annealing in steps of progressively increasing temperature has been used successfully [75Nag]. Thus, on the basis of available results, it appears that a fcc Cr-rich metastable phase may form in the initial stages of aging. 23Sie: E. Siedschlag, Z. Anorg. Chem., 131, 173-190 (1923) in German. 54Kos: W. Koster and W. Knorr, Z. Metallkd., 45, 350-356 (1954) in German. 57Doi1: T. Doi, J. Jpn. Inst. Met., 21(5), 337-340 (1957) in Japanese. 57Doi2: T. Doi, J. Jpn. Inst. Met., 21(12), 720-724 (1957) in Japanese. 75Nag: K. Nagata and S. Nishikawa, Rep. Inst. Ind. Sci., Univ. Tokyo, 24(4), Serial No. 153, 115-168 (Mar 1975). 77Kuz: G.M. Kuznetsov, V.N. Fedorov, and A.L. Rodnyanskaya, Izv. V.U.Z. Tsvetn. Metall., 3, 84-86 (1977) in Russian; TR: Sov. Non-Ferrous Met. Res., 3, 104- 105 (1977). 82Tim: L. Timberg and J.M. Toguri, J. Chem. Thermodyn., 14, 193-199 (1982). Published in Bull. Alloy Phase Diagrams, 5(4), Aug 1984. Complete evaluation contains 7 figures, 8 tables, and 37 references. 1