Anomalous Magnetic Behavior in Fe-Al Alloys

Abstract

Magnetic behavior of Fe-Al alloys with the composition in the neighborhood of 25 at%Al has been investigated by means of magnetic and Mössbauer measurements. A reliable phase constitution is determined for the atomic and magnetic ordering. Magnetic anomalies observed in this system can be satisfactorily interpreted in terms of our phase relationship. The variation of magnetization with quenching temperature shows a rapid increase in the intermediate temperature range owing to the appearance of the ferromagnetic disordered α phase. The so-called “double Curie point” phenomenon is primarily caused by the coexistence of the ferromagnetic phase with the paramagnetic one. The ratio of the phases, ferromagnetic α to paramagnetic B2, determines the magnetic intensity of the alloy depending on the composition and the cooling rate.