Magnetic Properties of σ-Phase of Some 3d-Transition Alloys

Magnetic susceptibility measurement has been made on the σ-phase of Fe-V, Co-V, Ni-V and Co-Cr binary alloys. The Fe-V system only is ferromagnetic. The temperature dependent parts of the susceptibility of Fe-V alloys obey the Curie-Weiss law. The paramagnetic moment µ per iron atom in Fe-V varies with vanadium concentration C v following an empirical relationship, µ/µ B =-2.62+173/ C v , where C v is atomic-% of vanadium. The Curie temperature is sensitive to heat treatments of the specimens, but the magnetic moment is not affected. The susceptibility of the other alloys is found to be nearly temperature independent. The magnitude of the magnetic moment localized on magnetic atoms at different kinds of sites in these σ-phase is suggested.