Magnetic properties and microstructures of Fe-Cr-10 wt% Co-M (M= Si/Ti/Ni/Mo/Ge/Ta) permanent magnet alloys

Effect of alloying elements and heat treatments on magnetic properties and microstructures of Fe-Cr-10 wt% Co alloys was studied by magnetic measurements and transmission electron microscopy (TEM). Among the alloying elements tried, it was found that only Si and Ti can greatly improve the hard magnetic properties of the Fe-Cr-Co alloys. An Fe-10Co-26Cr alloy added with 0.5 wt% Si-0.5 wt% Ti showed the best combination of magnetic properties of H_c = 43 kA/m.B_r = 1.42 T, (BH)_m = 41 kJ/m³.The variation in magnetic properties was correlated to quantitative microstructural features, particle size and aspect ration. It was found that for alloys of the same composition, H_c is determined by shape anisotropy induced by magnetic aging.