Recent progress in Fe-based amorphous and nanocrystalline soft magnetic materials

History of Fe-based amorphous and nanocrystalline soft magnetic alloys is reviewed and our recent progress in these materials in magnetic devices such as transformers is reported. For lower-rated transformers, a thinner Fe-based amorphous alloy ribbon is found to have an advantage for core loss due to the reduced residual bending stress at the corners of a wound core as well as smaller eddy current loss. For large transformer cores, a prototype Fe-based amorphous alloy ribbon-based stacked core is built using a 142 mm wide commercially available ribbon prepared by tension annealing. With the optimization of glue and joint technique for a stacked core, it is found that core loss of a stacked-core with a polyester glue and a step-lap joint is lower than that of a conventional wound core in the excitation range between 1 and 1.45 T at 50 Hz.