Фазовая диаграмма системы B-Fe

К оглавлению: Другие диаграммы (Others phase diargams)


B-Fe (Boron-Iron) P.K. Liao and K.E. Spear The equilibrium phases of the Fe-B system are (1) the liquid, L; (2) the terminal solid solutions-high-temperature bcc (dFe), medium-temperature fcc ( gFe), low-temperature bcc (aFe), and rhombohedral (bB)-characterized by small mutual solid solubility in the elements; and (3) two intermetallic compounds- Fe2B and FeB. Equilibrium compositions in the assessed phase diagram were obtained by least- squares optimization of the experimental thermochemical and phase diagram data of [Hansen], [69Por], [70Vor], [72Por], and [Kubaschewski]. A polynomial model was assumed for the excess Gibbs energy of the liquid. Agreement was very good between the calculated phase diagram and the experimental data. Single-phase Fe3B, which is widely recognized as a metastable phase, can be produced by quenching liquid Fe76B24 [82Kha]. Three modifications of Fe3B have been reported. Fe2B forms from the melt by a peritectic reaction, L + FeB = Fe2B, which occurs at 1389 с 20 C. FeB melts congruently at 1650 ‘ 60 C. Reported invariant and melting points range from 1389 to 1410 C and from 1540 to 1657 C for Fe2B and FeB, respectively. Both borides have a narrow homogeneity range of about 1 at.% B. 69Por: K.I. Portnoi, M.Kh. Levinskaya, and V.M. Romashov, Poroshk. Metall., 8( 80), 66-70 (1969) in Russian; TR: Sov. Powder Metall. Met. Ceram., 8, 657-659 ( 1969). 70Vor: L.G. Voroshnin, L.S. Lyakhovich, G.G. Panich, and G.F. Protasevich, Metalloved. Term. Obrab. Met., 9, 14-17 (1970) in Russian; TR: Met. Sci. Heat Treat. (USSR), 9, 732-735 (1970). 72Por: K.I. Portnoi and V.M. Romashov, Poroshk. Metall., 113(5), 48 (1972) in Russian. 82Kha: Y. Khan, E. Kneller, and M. Sostarich, Z. Metallkd., 73, 624-626 (1982). Submitted to the APD Program. Complete evaluation contains 5 figures, 6 tables, and 38 references. Special Points of the Fe-B System