Fe-Metalloid-Based Soft Magnetic Nanostructures for Efficient Automotive Applications

Fe-based nanocrystalline soft magnetic materials are potential low coercivity core materials for electrical motors. The targeted properties are saturation magnetic polarization above 1.9T. Fe-B binary alloys with Fe-content above 86at% can reach the 1.9T target but the nanocrystalline alloys have large bcc-Fe grains hence high coercivity after conventional annealing. This thesis reports that annealing with an ultra-high heating rate up to 9200K/s can trigger on the homogeneous nucleation in Fe-B alloys and result in dramatic grain refinement effect. Fe87B13 alloys processed by rapid annealing show a saturation magnetic polarization of 1.92T and a coercivity of 6.7A/m.