The nanocrystalline powders offer opportunities for the design of soft magnetic materials with improved magnetic properties (high saturation magnetization, high permeability, low magnetostriction) to be used for high frequency applications magnetic cores 1-4. The aim of the work is to develop Fe73.5Cu1Nb3Si13.5B9 powders with a high percentage of particles having the size in the range where nanocrystalline state is directly achieved, by using a new three-jet gas atomization technique (consisting in the use two jets of Ar gas and one jet of water), directed in such a configuration so that the molten alloy jet to be successively fragmented in droplets by the gas jets and further broken intro droplets and cooled by the liquid jet. Powders with the diameter size in the ranges 0-20 µm, 20-32 µm, 32-63 µm, and 63-100 µm have been prepared. Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), thermomagnetic, and magnetic measurements have been performed to assess the structural and magnetic differences of powders between the groups of samples after sieving. The SEM images revealed the formation of particles with almost spherical shape. The X-Ray diffraction patterns show that in the range 0-32 µm the structure of particles is a mixture of amorphous and nanocrystalline phases, approx. 50 % of particles being in amorphous state, which is a quite high percentage. The magnetic measurements, performed using the Vibrating Sample Magnetometer technique (VSM) show that the Curie temperature increases from 350°C to 520°C and the saturation magnetization is between 130 to 145 emu/g. The coercive field, Hc, takes a very low value of 4 Oe for as-cast powders with the smallest diameter range, the value decreasing to down to under 2 Oe after annealing. These properties combined with good thermal stability, low cost price, the possibility to develop components with reduced dimensions/masses, make the amorphous and nanocrystalline alloys competitive and economic solutions in electronics, telecommunications, sensors, etc.
Work supported by the Romanian Ministry of Research, Innovation and Digitalization under NUCLEU Program – contract no. 33N/2019, project PN 19 28 01 01.
1 T. Suzuki, P. Sharma, and L. Jiang, IEEE Trans. Magn., Vol. 54, 2801705 (2018)
2 L. Chang, L. Xie, and M. Liu, J. Magn. Magn. Mater., Vol. 452, p. 442 (2018)
3 K.L. Alvarez, J.M. Martín, and M. Ipatov, J. Alloys Compd., Vol. 735, p. 2646 (2018)
4 K. L. Alvarez, H.A. Baghbaderani, and J.M. Martín, J. Magn. Magn. Mater., Vol. 501, 166457, (2020)