The Effects of Thermomagnetic Treatment on the Magnetic Properties of Nanocrystalline Fe–O and Fe-Co–O Pressed Compacts

Abstract The influence of thermal and thermomagnetic treatment on the magnetic properties of iron—cobalt oxides compacts fabricated by powder metallurgy is studied. The influence of magnetic pulse processing (MPP) on the formation of the phase composition and magnetic properties of nanocrystalline α-Fe (50%) + Fe 2 O 3 (50%); α-Fe (50%) + Fe 2 O 3 (40%) + Co 3 O 4 (10%) and α-Fe (50%) + Fe 2 O 3 (30%) + Co 3 O 4 (20%) pressed powder compacts during synthesis in a high-energy mill and subsequent annealing have been investigated. According to the X-ray diffraction analysis, annealing α-Fe (50%) + Fe 2 O 3 (50%) pressed samples at 250 ℃ in air, promotes the oxidation of α-Fe and FeO to magnetite (Fe 3 O 4 ). Additional annealing of the compact in vacuum at 250 ℃ increases its remnant magnetization and magnetic anisotropy. Whereas, increasing the concentration of Co 3 O 4 oxide has no strong effect on the coercivity and residual magnetization of the compacts. Eventually, thermomagnetic treatment of the α-Fe (50%) + Fe 2 O 3 (30%) + Co 3 O 4 (20%) system does not improve its magnetic properties.