Papers by Keyword: Saturation Magnetisation

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Authors: Innocent Shuro, Minoru Umemoto, Yoshikazu Todaka, Ho Hung Kuo, Hong Cai Wang
Abstract: SUS 304 austenitic stainless steel (ASS) was deformed by high pressure torsion (HPT) to obtain 100% volume fraction of martensite (α') from a fully austenitic (γ) matrix. Deformation caused an increase in hardness (Hv) from 1.6 GPa in the as annealed state to 6.4 GPa after HPT. Deformed samples were then annealed in the range 200 – 600oC and peak hardness of 7.8 GPa was observed after annealing at 400oC for 1 hour. Differential scanning calorimetry (DSC) and electrical resistivity tests showed that the deformed alloy undergoes a two stage phase transformation on heating from room temperature up to 700oC. The first stage of transformation was associated with hardening behavior while the second one which is reverse α' → γ transformation resulted in a reduction in hardness. Annealing at 400oC after deformation was found to increase the magnetization saturation (Msat) values.
Authors: Ying Shan Chen, Wang Jun Feng, Cui Huan Li, Rui Shan Li, Rui Fan, Hua Yang
Abstract: Nanocrystalline nickel ferrite has been successfully synthesized through carbon-adsorb auto combustion method from Ni and Fe nitrate salts. The powders were characterized by X-raydiffraction(XRD) techniques,scanning electron microscopy(SEM),transmission electron microscopy(TEM) and vibrating sample magnetometry(VSM). XRD indicated that the products were spinel NiFe2O4. SEM and TEM indicated that the particles were spherical with particle size in the range 10-80nm. VSM showed that the sample exhibited typical ferromagnetic behavior at room temperature,while the coercivity of the sample was 150.45Oe and the residual magnetization of the sample was 5.1emu/g.The saturation magnetization of the sample(25.3emu/g)was lower than that for the reported bulk particles(55emu/g), and it has the ultrafine nature.
Authors: X.F. Han, L.Y. Lin, E. Baggio-Saitovitch, R.G. Xu, Xiao Hong Wang, H.G. Pan
Authors: Xin Wang, Hui Jia, Wei Tao Zheng, Wei Xu, Bei Hong Long
Abstract: Fe-Co-N thin films with various Co content were synthesized on Si (111) substrate using facing-target magnetron sputtering by changing sputtering input power on Co target. During deposition, the input power on Fe target was kept at 160 W. The composition, structure, and magnetic properties were examined by X-ray photoelectron spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), and superconducting quantum interference device. XRD and TEM investigations showed that at lower input power of 11.2 W on Co target, the phases in the film were -(Fe,Co)4N and Co3N. Increasing sputtering input power, the content of Co in the film increased. At input power of 14 W, film contained -(Fe,Co)8N phase was produced which exhibited higher saturation magnetization (252.85 Am2/kg) and lower value of coercivity (3.66 kAm-1), corresponded to the 12% content of Co in the film.
Authors: Wei Li, Ping Liu, Feng Cang Ma, Xin Kuan Liu, Xiao Hong Chen, Yong Hua Rong
Abstract: A nanocrystalline surface layer is produced in Co plate by surface mechanical attrition treatment (SMAT). The characterization of microstructure and composition indicates that elements of Fe, Cr diffuse from hardened steel balls into the surface layer during SMAT. The diffusion phenomenon results in the composition deviation in the surface layer, leading to higher value of saturation magnetization (Ms) for nanocrystalline Co surface layer in comparison with its coarse-grained counterpart.
Authors: Hiroyuki Matsumoto, Akiri Urata, Yasunobu Yamada, Akihisa Inoue
Abstract: The inductor for a power supply is expected to have higher efficiency and capability of dealing satisfactorily with large current. Additionally, high corrosion resistance characteristics are also required for commercial inductors in practical use of. Thereby, we focused on Fe-based glassy metal alloys with both high magnetization and low magnetic anisotropy [1], and developed the novel glassy metal alloys with a chemical composition Fe97-x-yPxByNb2Cr1. In this glassy metal alloy, 1 at % Cr is the optimum composition for the realization of higher corrosion resistance as well as a high magnetic flux density. The glassy Fe97-x-yPxByNb2Cr1 (x=5-13, y=7-15) alloy exhibits the high glass-forming ability leading to the large thickness of 110-150 μm and low coercive force of 2.5-3.1 A/m due to higher structural homogeneity in wide range of composition. The large critical thickness of this alloy should be caused by the high glass-forming ability (GFA) due to the existence of the super cooled liquid region (Tx) of roughly 30 K. Therefore a Fe77P7B13Nb2Cr1 powder/resin composite core displays a much lower core loss of 650 W/m3 than the conventional amorphous Fe75Si10B12Cr3 powder/resin composite core by approximately 1/3.
Authors: Marita Yusrini, Idris Yaacob Iskandar
Abstract: Nickel-Iron nanocrystalline alloys with different grain sizes were fabricated by electrodeposition technique. In this study, influence of the grain size nanocrystalline NiFe deposits on saturation magnetization Ms and coercivity Hc was investigated. Alternating gradient magnetometer (AGM) with up to 10 kOe applied magnetic field was used to study the magnetic properties of NiFe film. The results showed that saturation magnetization Ms and coercivity Hc were affected by grain size variation. Increase in grain size increased the saturation magnetization. The largest grain size of 18.6 nm showed the highest Ms of 138 emu/g, while the smallest grain size of 7.2 nm showed Ms of 94 emu/g. Minimum coercivity of 3.847 Oe was observed for sample with 7.2 nm grain sizes. The coercivities decreased for smaller grain sizes.
Authors: Hong Cai Wang, Minoru Umemoto, Innocent Shuro, Yoshikazu Todaka, Ho Hung Kuo
Abstract: SUS316L austenitic stainless steel was subjected to severe plastic deformation (SPD) by the method of high pressure torsion (HPT). From a fully austenitic matrix (γ), HPT resulted in phase transformation from g®a¢. The largest volume fraction of 70% a¢ was obtained at 0.2 revolutions per minute (rpm) while was limited to 3% at 5rpm. Pre-straining of g by HPT at 5rpm decreases the volume fraction of a¢ obtained by HPT at 0.2rpm. By HPT at 5rpm, a¢®g reverse transformation was observed for a¢ produced by HPT at 0.2rpm.
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