Abstract

Co-Fe-Ni-B-Si-Cr based amorphous strips containing nitrogen were manufactured via melt spinning, and then devitrified by crystallization treatment at the various annealing temperatures of 300°Csim540°C for up to 30 minutes in an inert gas (N_2) atmosphere. The microstructures were examined by using XRD and TEM and the magnetic properties were measured by using VSM and B-H meter. Among the alloys, the amorphous ribbons of Co_72.6Fe_9.8Ni_5.5B_2.4Si_7.1Cr_2.6 containing 121 ppm of nitrogen showed relatively high saturation magnetization. The alloy ribbons crystallized at 540°C showed that the grain size of Co_72.6Fe_9.8Ni_5.5B_2.4Si_7.1Cr_2.6 alloy containing 121 ppm of nitrogen was about f nm, which exhibited paramagnetic behavior. The formation of nano-grain structure was attributed to the finely dispersed Fe4N particles and the solid-solutionized nitrogen atoms in the matrix. Accordingly, it can be concluded that the nano-grain structure of 5nm in size could reduce the core loss within the normally applied magnetic field of 300A/m at 10kHz.

• Keywords: Co-based amorphous strip;Nitrogen and Fe additions;Core loss;Saturation magnetization;