Фазовая диаграмма системы Cu-W

К оглавлению: Другие диаграммы (Others phase diargams)

Cu-W (Copper-Tungsten) P.R. Subramanian and D.E. Laughlin [Hansen] established from the reports of [06Gui], [15Rum], and [31Sch] that W is insoluble in liquid Cu. The so-called Cu-W "alloys" reported in the literature [31Sch, 82Pan] were prepared by liquid-phase sintering of mechanical mixtures of Cu and W powders at temperatures greater than the melting point of Cu. Phase equilibria studies of the ternary systems W-Cu-Al [ 83Pre] and W-Cu-WSi2, [84Efi] reported negligible mutual solubilities of Cu and W at 597 and 797 C, respectively. The equilibrium phases of the assessed Cu-W phase diagram are (1) the liquid, L, with a miscibility gap (L1 + L2); (2) the fcc terminal solid solution, (Cu), with extremely limited solid solubility of W; and (3) the bcc terminal solid solution, (W), with extremely limited solid solubility of Cu. The assessed phase diagram is based on a simple thermodynamic model [83Nie] and should be regarded as speculative because no experimental parameters are involved. Moreover, the thermodynamic model may be too simplistic. The general pattern of phase relationships in the Cu-W system closely follows that for the Cu-Mo system. This is to be expected in view of the close similarity between Mo and W. [74Poa] reported that alloying of Cu by room temperature W ion implantation resulted in the formation of an almost 90% substitutional solid solution, while annealing at 500 C for 1 h reduced the substitutionality to ~70%. Ion implantation studies by [76Cul] show that, for W implant concentrations of <1 at.%, W is in solid solution, whereas implant concentrations of ~10 at.% W resulted in the formation of disordered Cu and W layers with the W atoms occupying no regular lattice sites. Annealing the implanted specimens at ~450 C resulted in the formation of bcc precipitates. [85Dir] studied co-evaporated Cu1-xWx alloy films by TEM, X-ray, electron diffraction, and electrical resistivity. Their results indicate a significant increase in mutual solid solubilities. The metastable (fcc + bcc) two-phase coexistence region was estimated to lie between 40 to 60 at.% W. [85Nas] prepared amorphous thin films of Cu-W in the composition range 28 to 55 at.% W by co-evaporation. Examination of the as-deposited specimens as well as specimens subjected to subsequent treatments such as thermal annealing and ion irradiation showed the formation of various intermediate metastable structures. 06Gui: L. Guillet, Rev. M‚tall., 3(1), 149-179 (1906) in French. 15Rum: O. Rumschottel, Met. Erz, 12, 45-50 (1915) in German. 31Sch: K. Schroter, Z. Metallkd., 23, 197-201 (1931) in German. 74Poa: J.M. Poate, W.J. DeBonte, W.M. Augustyniak, and J.A. Borders, Appl. Phys. Lett., 25(12), 698-701 (1974). 76Cul: A.G. Cullis, J.M. Poate, and J.A. Borders, Appl. Phys. Lett., 28(6), 314-316 (1976). 82Pan: V.V. Panichkina, M.M. Sirotyuk, and V.V. Skorokhod, Porosh. Metall., (6) , 27-31 (1982) in Russian; TR: Sov. Powder Metall. Met. Ceram., 21(6), 447-450 (1982). 83Pre: A.P. Prevarskii and Y.B. Kuz'ma, Russ. Metall., 5, 187-189 (1983). 83Nie: A.K. Niessen, F.R. de Boer, R. Boom, P.F. de Chatel, W.C.M. Mattens, and A.R. Miedema, Calphad, 7(1), 51-70 (1983). 84Efi: Y.V. Efimov, T.M. Frolova, O.I. Bodak, and O.I. Kharchenko, Izv. Akad. Nauk SSSR, Neorg. Mater., 20(9), 1593-1595 (1984) in Russian. 85Dir: A.G. Dirks and J.J. van den Broek, J. Vac. Sci. Technol. A, 3(6), 2618- 2622 (1985). 85Nas: M. Nastasi, F.W. Saris, L.S. Hung, and J.W. Meyer, J. Appl. Phys., 58(8) , 3052-3058 (1985). Submitted to the APD Program. Complete evaluation contains 1 figure, 3 tables, and 21 references. 1