Фазовая диаграмма системы Al-Hf

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Al-Hf (Aluminum-Hafnium) J.L. Murray, A.J. McAlister, and D.J. Kahan Only [60Rat], [62Pot], and [70Tsy] have studied phase equilibria in the Hf-Al system. The assessed (provisional) phase diagram is based primarily on review of their work. [60Rat] investigated the solubility of Hf in solid (Al) and the liquid and reported that the maximum solid solubility is 0.186 at.% Hf at the peritectic temperature of 662.2 C. The solubility of Al in (aHf) is 23 to 25 at.% Al at 1400 C [70Tsy]. The maximum solubility of Al in (bHf) is about 33 at.% Al at about 1520 C [70Tsy]. All intermediate phases appear to have very limited solubility ranges. The bHfAl3 = aHfAl3 transformation, which occurs at about 650 C, was studied metallographically by [62Pot], who found the microstructure of a sample partially transformed on cooling to be compatible with that expected of peritectoid and aHfAl3 to be slightly Al rich with respect to bHfAl3. This construction is in agreement with the observed persistence of bHfAl3 rather than aHfAl3 after long heat treatment at 450 C. [82Hor] reports that up to 0.96 at.% Hf can be dissolved metastably in (Al) by splat quenching. Fast quenching of alloys containing up to 1.6 at.% Hf produces, in addition to supersaturated (Al), a metastable phase with the L12 AuCu3 structure here labeled gHfAl3 [82Hor]. This phase is long lived, enduring for up to 900 h at 450 C. After even longer aging, it transforms to bHfAl3. 60Bol: H. Boller, H. Nowotny, and A. Wittman, Monatsh. Chem., 91, 1174-1184 ( 1960) in German. 60Eds1: L.E. Edshammar and S. Anderson, Acta Chem. Scand., 14, 223-224, (1960). 60Eds2: L.E. Edshammar, Acta Chem. Scand., 14, 1220 (1960). 60Eds3: L.E. Edshammar, Acta Chem. Scand., 14, 2244 (1960). 60Rat: B.B. Rath, G.P. Mohanty, and L.F. Mondolfo, J. Inst. Met., 89, 248-249 ( 1960-61). 60Sch: K. Schubert, T.R. Anantharaman, H.O.K. Ata, H.G. Meissner, M. P”tschke, W. R”ssteutscher, and E. St”lz, Naturwissenshaften, 47, 512 (1960) in German. 61Bol: H. Boller, H. Nowotny, and A. Wittmann. Monatsh, Chem., 92, 324-331 ( 1961) in German. 61Dwi: A.E. Dwight, J.W. Downey, and R.A. Conner, Acta Crystallogr., 14, 75-76 (1961). 61Eds: L.E. Edshammar, Acta Chem. Scand., 15, 403-406 (1961). 61Now: H. Nowotny, O. Schob, and F. Benesovsky, Monatsh. Chem., 92, 1300-1303 ( 1961) in German. 62Pot: M. Potzschke and K. SchЃbert, Z. Metallkd., 53, 548-561 (1962) in German. 70Tsy: I.A. Tsyganova, M.A. Tylkina, and E.M. Savitskiy, Izv. Akad. Nauk. SSSR Metallurgy, 1, 160-163 (1970) in Russian; TR: Russ. Metall., 1, 107-109 (1970). 82Hor: S. Hori and N. Furushiro, Jpn. Inst. Met., 2, 1525-1528 (1982). Submitted to the APD Program. Complete evaluation contains 2 figures, 3 tables and 17 references. Special Points of the Hf-Al System