Iron Aluminides and Related Phases

An overview of the Fe- Al phases is given by the binary Fe-Al phase diagram (Massalski et al., 1990). The Al-rich phases with melting temperatures of about 1150 °C are of interest for Al alloys and are not addressed here. The remaining phases FejAl and FeAl, and related phases, have been selected for materials developments because of their outstanding physical, mechanical, and chemical properties and are the subjects of the following sections. 

FcjAl is formed on cooling by ordering reactions in the solid state that transform the b.c.c. disordered solid solution, which 

Thermal vacancies are formed readily because of a low formation enthalpy. 

The plastic deformation, including twinning, of FcjAl and the effect of atomic order on strength and ductility has been studied in detail (Marcinkowski and Brown, 1961 Stoloff and Davies, 1964, 1966 Morgand etal., 1968 Leamy and Kayser, 1969 Marcinkowski, 1974 a Ha-nada et al., 1981 a, b Park et al., 1991 Eh-lers and Mendiratta, 1984 Schroer et al.. 

Finally, it is noted that such perovskite-type phases are also formed in other alloy systems by alloying with carbon as well as with oxygen, and that such phases are considered for strengthening intermetallic alloys (Goldschmidt, 1967 a Nowotny, 

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