Фазовая диаграмма системы Al-N

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Al-N (Aluminum-Nitrogen) H.A. Wriedt The established equilibrium solid phases of the Al-N system are (1) the fcc terminal solid solution, (Al), and (2) the hexagonal nitride AlN. The assessed Al-N diagram is primarily qualitative, because of the lack of data on the composition ranges of the solid and liquid phases. It was obtained by thermodynamic calculation and review of the experimental data [Hultgren,E, 26Iwa, 46Eas, 59Vol, 74Sch1, 74Sch2, 78Cha, 79Bor]. The eutectic near the melting point of Al and the monotectic near that of AlN are speculative; the respective displacements in temperature of these reactions from the melting points of pure Al and of stoichiometric AlN are believed to be slight. The phase (Al) exists stably only at very small nitrogen (N2) fugacities; at greater N2 fugacities, AlN is stable. The N concentrations in (Al) that are in equilibrium with AlN and the (Al) solidus have not been measured. An Al-rich liquid, L1, exists stably at small N2 fugacities. No experimental data on the Al-rich liquidus of L1 or of the location of the probable eutectic reaction at its termination exist. The composition of the eutectic liquid is estimated to be ~1 x 10-11 at.% N. The N-saturated L1, with very small N concentrations, is in equilibrium with AlN from the temperature of the eutectic reaction to that of the monotectic reaction; compositions of this liquid have not been measured. At low hydrostatic pressures, the nitride AlN has a wurtzite-type hP4 structure. AlN transforms at elevated hydrostatic pressures from the wurtzite- type structure to a possibly sphalerite-type cF8 structure [68Ver] or to a NaCl-type cF8 structure [82Kon]. Up to the monotectic temperature, where it coexists with Al-rich L1 and N-rich L2, AlN is in equilibrium with (Al) or L1 on its Al-rich side. The value 2800 с 50 C for the melting point of AlN was reported by [68Cla], who used high- pressure N2 to retard evaporation. There are no experimental data for the L2 liquidus from the melting point of AlN to the monotectic reaction or for the monotectic reaction itself. The compositions of the immiscible liquids L1 and L2 coexisting above the monotectic temperature are unknown. The phase AlN9 was reported to be formed by reaction of NH3 with AlH3 in an ether solution at a temperature slightly above the melting point of the solvent [54Wib1] and by reaction of NaN3 with AlCl3 in tetrahydrofuran [54Wib2] . This nitride may be a stable phase of the condensed Al-N system. 26Iwa: K. Iwas‚, Sci. Rep. Tohoku Imp. Univ., Ser. 1, 15(4), 531-566 (1926). 46Eas: L.W. Eastwood, Gases in Light Alloys, John Wiley & Sons, New York, 26 ( 1946). 54Wib1: E. Wiberg and H. Michaud, Z. Naturforsch., 9b, 495-496 (1954) in German. 54Wib2: E. Wiberg and H. Michaud, Z. Naturforsch., 9b, 496-497 (1954) in German. 59Vol: A.E. Vol, Handbook of Binary Metallic Systems-Structures and Properties, Vol. 1, Gos. Izd. Fiz.-Mat. Lit., Moscow (1959). 68Cla: W. Class, NASA Contract Rep. NASA CR-1171 (1968). 68Ver: L.F. Vereschagin, G.A. Adadurov, O.N. Breusov, K.P. Burdina, L.N. Burenkova, A.N. Dremin, E.V. Zubova, and A.I. Rogacheva, Dokl. Akad. Nauk SSSR, 182(2), 301-303 (1968) in Russian. 74Sch1: A. Schweighofer and S. KЈdela, Kovove Mater., 12(1), 95-107 (1974) in Slovak. 74Sch2: A. Schweighofer and S. KЈdela, Kovove Mater., 12(2), 268-279 (1974) in German. 78Cha: M.W. Chase, Jr., J.L. Curnutt, R.A. McDonald, and A.N. Syverud, J. Phys. Chem. Ref. Data, 7(3), 793-794 (1978). 79Bor: P.C. Borbe, F. Erdmann-Jesnitzer, and E.-J. Jun. Metall, 33(10), 1054- 1060 (1979) in German. 82Kon: K. Kondo, A. Sawaoka, K. Sato, and M. Ando, Shock Waves in Condensed Matter-1981, AIP Conf. Proc. No. 78, Am. Inst. Phys., NY, 325-329 (1982). Published in Bull. Alloy Phase Diagrams, 7(4), Jun 1986. Complete evaluation contains 1 figure, 4 tables, and 60 references. Special Points of the Al-N System