Фазовая диаграмма системы Al-La

К оглавлению: Другие диаграммы (Others phase diargams)

Al-La (Aluminum-Lanthanum) K.A. Gschneidner, Jr. and F.W. Calderwood The assessed phase diagram for the Al-La system is based primarily on the work of [65Bus], with review of the work of [67Gom] and [69Dri]. The melting temperatures of the elements have been adjusted to agree with the accepted values of [Melt]. The Al-La system is characterized by six intermediate phases: Al11La3, Al3La, AlxLa, Al2La, AlLa, and AlLa3. The Al-rich compound, Al11La3, undergoes an a = b transition at 915 C. The b phase has tetragonal symmetry with the Al4Ba- type structure and forms congruently at 1240 C. Al3La has hexagonal symmetry with the Ni3Sn-type structure and forms peritectoidally at 1170 C from b Al11La3 and AlxLa. AlxLa is stable only between 1090 and 1240 C. It forms peritectically at 1240 C from Al2La and the melt and, on cooling, decomposes to Al2La and Al3La at 1090 C. Al2La forms congruently at 1405 C. AlLa and AlLa3 are formed peritectically, at 873 C from Al2La and the melt, and at 550 C from AlLa and the melt, respectively. The eutectic composition between Al and Al11La3 is about 3 at.% La at the eutectic temperature of 640 C. A eutectic between bAl11La3 and AlxLa occurs at 1220 C and 24 at.% La. The third eutectic (between AlLa3 and La) has a composition of 76.7 at.% La and occurs at 547 C. The addition of a few percent of Al to pure La caused a slight decrease in lattice parameters, thus indicating slight solubility of Al in La. The solid solubility of La in Al is 0.01 at.% at 640 C [69Dri]. 65Bus: K.H.J. Buschow, Philips Res. Rep., 20, 337 (1965). 67Gom: A.H. Gomes de Mesquita and K.H.J. Buschow, Acta Crystallogr., 22, 497 ( 1967). 69Dri: M.E. Drits, E.S. Kadaner, and N.D. Shoa, Izv. Akad. Nauk SSSR, Met., (1) , 219 (1969); TR: Russ. Metall., (1), 113 (1969). Published in Bull. Alloy Phase Diagrams, 9(6), Dec 1988. Complete evaluation contains 1 figure, 1 table, and 31 references. 1