Preparation of amorphous Fe-based magnetic powder by water atomization

Fe-Si-B-C-P amorphous powders were fabricated successfully by water atomization. The morphology, chemical composition, phase structure and soft magnetic properties were then studied in this work. The results indicate that the powders are completely amorphous in nature. DSC analyses show that the powders have a glass transition temperature T(g) about 768 K and a crystallization temperature T(x) about 816 K, which are almost the same to those of the bulk form. The morphology of the powders can be modified by adjusting the water atomization parameters, and both dendritic particles and spherical particles can be made. Compared with the gas-atomized powders and the bulk form made by casting, the water-atomized powders contain a higher amount of oxygen (about 1800 ppm), and also a higher content of Fe. It suggests that the high content of oxygen impurity may further increase the glass forming ability and a higher content of Fe may increase the saturation magnetization of the material. The water-atomized powders can be easily densified into bulk forms. The soft magnetic properties depend on the densification and heat treatment temperatures. The bulk Fe-based metallic glass, made by using the water-atomized powders, has a saturation magnetization as high as 1.64 T and a value of coercivity as low as 5.9 A/m. Therefore, the water-atomized powders are very cost-effective and suitable for industrial applications. (C) 2011 Elsevier B.V. All rights reserved.