Fabrication and Soft Magnetic Properties of Fe81.3Si4B10P4Cu0.7 Amorphous Powders by Using the Spinning-water Atomization Process

Soft magnetic Fe81.3Si4B10P4Cu0.7 powders have been fabricated by using spinning-water atomization process (SWAP) under the water pressure of 17.5 MPa and gas pressure of 2 MPa. To clarify the amorphous forming ability, thermal stability, and the corresponding soft magnetism, the as-SWAPed powders have been sieved into 6 groups with different powder sizes of 0 – 150 μm. After the analysis of the amorphous and crystalline characteristics, the morphology, and soft magnetic properties of these 6 groups of as-SWAPed powders, it is concluded that the SWAPs with a high cooling rate about 10⁵ K/s can improve the amorphous forming abilities of Fe81.3Si4B10P4Cu0.7 powders up to 53 μm, the saturated magnetic flux density as high as 170 – 173 emu/g and the thermal stabilities higher than 112.8 K. The characteristic parameters of as-SWAPed powders above mentioned are close to those of the counterpart rapid solidified ribbons. The surface oxide layers on as-SWAPed powders mainly consist of Fe3O4 and SiO2, and are 10 nm thick, much thicker than these counterpart ribbons, which might help to weaken the eddy effects accompanying with the slight decrease of the saturated magnetic flux density. Due to the higher cooling rates of SWAPs than gas atomization processes and the better spheroidization of powders for SWAPs than water atomization processes, it is key for NANOMET® family alloys to increase their amorphous forming abilities and better the soft magnetic performances.