Diffusionless Nucleation of Lonsdaleite and Diamond in Hexagonal Graphite under Static Compression
Tóm tắt
We have used transmission electron microscopy to study the initial stages of diffusionless formation of lonsdaleite and diamond crystals when pyrolytic graphite is subjected to static compression. We consider the effect of plastic deformation of the matrix phase on development of the transformation. We propose a dislocation model for nucleation of dense phases, making it possible to explain the reason for the formation of a metastable lonsdaleite phase, the nature of its structural disordering, and also the possibility of diffusionless nucleation of diamond directly from hexagonal graphite.
Tài liệu tham khảo
F. P. Bundy and J. S. Kasper, “Hexagonal diamond — a new form of carbon,” J. Chem. Phys., 46,No. 9, 3437–3446 (1967).
A. V. Kurdyumov and A. N. Pilyankevich, Phase Transformations in Carbon and Boron Nitride [in Russian], Nauk. Dumka, Kiev (1979).
D. V. Fedoseev, B. V. Deryagin, I. T. Varshavskaya, and A. S. Semenova-Tyan-Shan'skaya, Crystallization of Diamond [in Russian], Nauka, Moscow (1984).
A. V. Kurdyumov and N. I. Borimchuk, “Mechanism for transformation of rhombohedral graphite to diamond,” Dokl. Akad. Nauk SSSR, 297,No. 3, 602–604 (1987).
A. V. Kurdyumov and G. S. Oleinik, “Metastable structures of graphite-like boron nitride,” Kristallografiya, 29,No. 4, 792–793 (1984).
V. D. Blank, N. F. Borovikov, and N. R. Serebryanaya, “Direct graphite — diamond transition at room temperature and its transformation mechanism,” in: The Effect of High Pressures on Matter [in Russian], Institute for Problems of Materials Science, National Academy of Sciences of Ukraine, Kiev (1994), pp. 10–16.
V. F. Britun, A. V. Kurdyumov, V. B. Zelyavskii, and I. A. Petrusha, “X-ray diffraction study of texture evolution in CVD-BN during phase transformations of the rhombohedral modification at high pressures and temperatures,” Sverkhtverdye Materialy, No. 4, 7–14 (2001).
V. I. Levitas, “Phase transitions in elastoplastic materials: continuum thermomechanical theory and examples of control. Part 1,” J. Mech. Phys. Sol., 45,No. 6, 923–947 (1997).
V. F. Britun and A. V. Kurdyumov, “Analysis of the effect of compression conditions on martensitic transformations of graphite to lonsdaleite and diamond,” Fizika i Tekhnika Vysokikh Davlenii, 11,No. 3, 34–42 (2001).
A. V. Kurdyumov, N. F. Ostrovskaya, and A. N. Pilyankevich, “Actual structure of diamonds made by dynamic synthesis,” Poroshk. Metall., No. 1, 34–40 (1988).
V. A. Solov'ev, “Mechanisms for the formation of new phase on stacking faults. Kinetic types for their action,” Fizika Metallov i Metallovedenie, 41,No. 5, 942–950 (1976).
J. P. Hirth and J. Lothe, Theory of Dislocations [Russian translation], Atomizdat, Moscow (1972).