Magnetic Properties of the FeAl sub 1--x Cu sub x System

• Published in: Journal of applied physics 1984-11, Vol.57 (8-IIA), p.3241-3243
• Main Authors: Saleh, A S, Mankikar, R M, Yoon, S, Okpalugo, D E, Booth, J G
• Format: Article
• Language: English
• ISSN: 0021-8979

The substitution of a 3d transition metal (T) for Al in the equiatomic intermetallic compound FeAl results in the onset of ferromagnetism beyond a certain critical concentration of (T). The system appears magnetically and structurally similar to the equivalent Co(TaT) alloys for which the critical concentration appeared to be related to an average electron concentration parameter. Copper substitution in FeAl, i.e., the series FeAl sub 1--x Cu sub x is discussed. It was found using X-ray and neutron diffraction techniques that the alloys remain single phase up to x = 0.35 and that the crystallographic order remains B2 throughout. The site occupancy has also been determined and compared with the predictions of theoretical models. Ferromagnetism is observed to occur in the alloys with x > 0.2. For these ferromagnetic alloys the inverse suceptibility against temp. curves (for T > T sub c ) all have the same slope independent of composition suggesting an interpretation in terms of an itinerant model. This interpretation is also supported by Rhodes--Wohlfarth plot. A region of superparamagnetism presages the onset of ferromagnetism and from this the size of the magentic clusters is estimated to be 20-25 A in radius. 6 ref.--AA