Note on the enthalpies of formation of Cu 3 Si and Cu 3 Ge
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This work is part of a research project concerned with controlled rolling of niobium steel. [7-~~ The authors would like to express their deep thanks to Professor Gu Deji, President of the Shanghai Society of Metals, for his help. The authors also thank the Shanghai No. 1 Iron and Steel Works for supplying experimental steel. REFERENCES 1. H.J. McQueen and J.J. Jonas: Treatise on Materials Science and Technology, Plastic Deformation of Materials, Academic Press, New York, NY, 1975, vol. 6, pp. 393-493. 2. A.H. Ucisik, I. Weiss, H.J. McQueen, and J.J. Jonas: Can. Metall. Q., 1980, vol. 19 (4), pp. 351-58. 3. C.M. Sellars and W.J McG. Tegart: Int. Met. Rev., 1973, vol. 17, pp. 1-24. 4. M. Lamberigts and T. Greday: The Hot Deformation of Austenite, AIME, New York, NY, 1976, pp. 286-315. 5. M.J. Stewart: The Hot Deformation ofAustenite, AIME, New York, NY, 1976, pp. 233-49. 6. A. Streisselberger, R. Kaspar, and O. Pawelski: Metall. Trans. A, 1985, vol. 16A, pp. 67-72. 7. Z.S. Li, G.Y. Zhang, Z.G. Dong, J.M. YANG, Z.L. Zheng, and P.X. Wang: Proc. Int. Conf. THERMEC-88, Iron Steel Inst. Japan, Tokyo, 1988, vol. 1, pp. 208-15. 8. Z.S. Li, Z.L. Zheng, P.X. Wang, and G.Y. Zhang: Acta Metalt. Sin., 1985, vol. 21 (1), pp. B24-B34. 9. Z.S. Li, G.Y. Zhang, Z.L. Zheng, and P.X. Wang: Chin. J. Met. Sci. Technol., 1986, vol. 4, pp. 350-58. 10. Z.S. Li, G.Y. Zhang, P.X. Wang, and Z.L. Zheng: J. Iron Steel Res., 1989, vol. 1 (3), pp. 29-35.
Note on the Enthalpies of Formation of Cu3Si and Cu3Ge S.V. MESCHEL and O.J. KLEPPA During recent years, systematic studies of the thermochemistry of transition metal silicides and germanides have been pursued in this laboratory, t~-6] In these studies, the enthalpies of formation of a number of silicides and germanides of the 3d and 4d transition metals have been measured. In the present communication, such data are reported for Cu3Si and Cu3Ge. While experimental values for the enthalpies of liquid-liquid mixing of (Cu + Si) and (Cu + Ge) have been reported in the literature, we have found no corresponding information for the considered solid compounds. However, in a recent thermodynamic assessment of the (Cu + Si) system by Liidecke, [7] a value for the enthalpy of formation of solid Cu3Si was calculated. In the view of the present authors, this calculated value seemed unrealistically low. This led us to initiate the present investigation of Cu3Si and Cu3Ge. A comparison between the new enthalpies of formation and data for liquid-liquid mixing allows us to calculate approximate values of the enthalpies and entropies of fusion for the considered compounds. Our new results are also compared with predicted values based on Miedema's semiempirical model, rSl The experiments were carded out in a high-temperature reaction calorimeter which is described in detail in a recent communication, tg~ According to the known phase diagrams, u~ the compounds Cu3Si and Cu3Ge both have congruent melting points which lie well below the operating temperature of our calorimeter. Hence, these two compounds were obvi
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