Structural properties and magnetic behavior in CoFe1−xAlx alloys

Structural properties and magnetic behavior in CoFe1−xAlx ternary alloys are studied as functions of composition (0≤x≤1) and quenching temperature (773–1273 K). The B2-phase exists stably over wide ranges of composition and temperature and the Heusler (L21)-phase appears around the stoichiometric composition (0.4≤x≤0.6) below about 973 K. In the B2-phase region, the mean magnetic moment decreases nearly linearly with increase in x. Furthermore, the moment decreases with increase in quenching temperature in x<0.4, while it remains almost constant in x≥0.4. In the Heusler-phase region, the mean magnetic moment has nearly the same value as that in the B2-phase, and shows no remarkable quenching temperature dependence. The correlation between the magnetic behavior observed in both phases and the point defect properties is discussed in terms of the long-range order (LRO) parameters.