Al addition effect on structure and magnetic properties in high Bs Fe-Cu-Si-B alloys

The effect of Al addition on the soft magnetic properties, microstructure and nanocrystallization characteristics for Fe-Cu-Si-B alloy system was investigated from the viewpoint of the kinetics of Cu clustering. The excellent magnetic softness is found in Fe80.5Cu1.5Si4B14-xAlx(x = 0, 1, 2, 3) alloy system. A lower coercivity of 10.2 A/m and a higher saturation magnetic flux density of 1.84 T are obtained in 370 degrees C-annealed Fe80.5Cu1.5Si4B13Al1 alloy. Different from other Al-containing alloys, the Fe80.5Cu1.5Si4B11Al3 alloy exhibits a different crystallization behavior and a significantly deteriorated coercivity. Although an increase of Al results in a small decline in saturation magnetic flux density and Curie temperature of amorphous phase, the 1 at. % Al addition is found to be effective in decreasing the onset temperature of primary crystallization T-x1 and refining the grain size, therefore helps in reducing the coercivity.