- Effect of Crystallization Treatment on the Magnetic Properties of Amorphous Strips Based on Co-Fe-Ni-B-Si-Cr Containing Nitrogen
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H.J. Cho, H.T. Kwon, H.H. Ryu, K.Y. Sohn, B.S. You, W.W. Park
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J Korean Powder Metall Inst. 2006;13(4):285-289.
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DOI: https://doi.org/10.4150/KPMI.2006.13.4.285
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 Abstract
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- 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.
- Effect of Grain Size Control and Binder Additions on the Soft Magnetic Properties of Fe-based Nanocrystalline Powder Cores
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E.K. Cho, H.J. Cho, H.T. Kwon, E.M. Cho, H.H. Ryu, K.Y. Sohn, W.W. Park
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J Korean Powder Metall Inst. 2006;13(4):256-262.
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DOI: https://doi.org/10.4150/KPMI.2006.13.4.256
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Abstract
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- The amorphous Fe_73Si_16B_7Nb_3Cu_1 alloy strip was pulverized to get a flake-shaped powder after annealing at 425°C for 90 min and subsequently ground to obtain finer flake-shaped powder by using a ball mill. The powder was mixed with polyimide-based binder of 0.5sim3wt%, and then the mixture was cold compacted to make a toroidal powder core. After crystallization treatment for 1 hour at 380sim600°C, the powder was transformed from amorphous to nanocrystalline with the grain size of 10sim15nm. Soft magnetic characteristics of the powder core was optimized at 550sim600°C with the insulating binder of 3wt%. As a result, the powder core showed the outstanding magnetic properties in terms of core loss and permeability, which were originated from the optimization of the grain size and distribution of the insulating binder.
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