Microstructure and magnetic properties of soft magnetic powder cores of amorphous and nanocrystalline alloys

With the development of modern ferromagnetic technology, soft magnetic powder cores (MPCs) of amorphous and nanocrystalline alloys have been intensively studied for their excellent soft magnetic properties such as high flux density, low coercivity and reduced core loss due to amorphous state and nanocrystalline grains of 10-20 nm dispersed in a residual amorphous matrix. In this paper, the microstructures and soft magnetic properties, i.e., maximum magnetic induction B-m, effective permeability mu(e), DC-bias properties and volume power losses P-CV of MPCs made from amorphous powder of gas atomization and nanocrystalline powder of pulverized melt-spun ribbon were investigated and also compared on the basis of the same level of mu(e). It is found that ne of both kinds of MPC keeps unchanged up to 1 MHz. The amorphous MPC has lower P-CV at lower frequency range, while the nanocrystalline MPC has lower P-CV at high frequency range instead. Also, the nanocrystalline MPC has better DC-bias property. Moreover, the DC magnetic properties and the changes of P-CV of both MPCs with frequency and flux density are also studied. Furthermore, the electromagnetic characteristics, the microstructures and the mechanisms accounting for these phenomena of both MPCs are also discussed. (C) 2012 Elsevier B.V. All rights reserved.