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T Sakurai - One of the best experts on this subject based on the ideXlab platform.

  • nanocrystalline structural evolution in fe90zr7b3 soft Magnetic Material
    Acta Materialia, 1996
    Co-Authors: Yan Zhang, K Hono, Akihisa Inoue, Akihiro Makino, T Sakurai
    Abstract:

    Abstract Primary crystallization process of an Fe90Zr7B3 amorphous alloy has been studied by atom probe field ion microscopy (APFIM) and transmission electron microscopy (TEM). It is confirmed that two phases coexist at the stage with optimum Magnetic properties, one is the α-Fe phase and the other is the amorphous phase enriched with Zr and B. Zr is almost completely rejected from the α-Fe phase, but some amount of B remains dissolved in the α-Fe phase. The as-quenched alloy is amorphous possibly with the median range order (MRO) structure. Unlike previously published results, no evidence for compositional decomposition prior to the crystallization reaction was found. This suggests that the crystallization progress by the nucleation and growth mechanism, and that redistribution of Zr and B from the crystallized phase to the amorphous matrix controls the grain growth. In fact, during the nucleation and growth stage, enrichment of Zr was found in front of the growing interface of the α-Fe particles, suggesting that the grain growth was controlled by the diffusion of Zr.

  • the microstructure evolution of a fe73 5si13 5b9nb3cu1 nanocrystalline soft Magnetic Material
    Acta Metallurgica Et Materialia, 1992
    Co-Authors: K Hono, Akihisa Inoue, K Hiraga, Q Wang, T Sakurai
    Abstract:

    Abstract The microstructure evolution in the course of crystallization of a splat-quenched Fe73,5Si13.5B9Nb3Cu1 amorphous alloy was investigated by atom probe field ion microscopy (APFIM) and high resolution transmission electron microscopy (HRTEM). All the alloying elements were found to be distributed homogeneously as an amorphous solid solution in the as-quenched state. At an initial stage of annealing, a concentration fluctuation of Cu was found to occur. Cu formed clusters of a few nanometer diameter and their composition was found to be approximately 30 at.% Cu at the beginning. In the later stage, a b.c.c. FeSi solid solution and the B and Nb enriched amorphous phase with the smaller Si content were found to coexist. In addition to these two phases, Cu enriched particles containing approximately 60 at.% Cu were found to be present in the intergranular regions, although we were not successful yet to determine whether this was a crystalline or amorphous phase. Based on these observations, we discuss the crystallization process of this alloy at 550°C which leads to the emergence of excellent soft Magnetic properties.

  • atom probe analysis of fe73 5si13 5b9nb3cu1 nanocrystalline soft Magnetic Material
    Applied Physics Letters, 1991
    Co-Authors: K Hono, A Inoue, T Sakurai
    Abstract:

    The microstructure of Fe73.5Si13.5B9Nb3Cu1 soft Magnetic Material with a nanocrystalline structure has been investigated by atom probe field ion microscopy. In the as‐quenched amorphous sample, all the alloying elements were found to distribute homogeneously as an amorphous solid solution. In the annealed sample with the optimum soft Magnetic properties, we found that two phases were present. One was Fe‐Si solid solution and the other was the B‐ and Nb‐enriched region with less Si content. Although some uncertainty remains regarding Cu, the present result is consistent with an early speculation based on the lattice parameter measurement.

K Hono - One of the best experts on this subject based on the ideXlab platform.

  • nanocrystalline structural evolution in fe90zr7b3 soft Magnetic Material
    Acta Materialia, 1996
    Co-Authors: Yan Zhang, K Hono, Akihisa Inoue, Akihiro Makino, T Sakurai
    Abstract:

    Abstract Primary crystallization process of an Fe90Zr7B3 amorphous alloy has been studied by atom probe field ion microscopy (APFIM) and transmission electron microscopy (TEM). It is confirmed that two phases coexist at the stage with optimum Magnetic properties, one is the α-Fe phase and the other is the amorphous phase enriched with Zr and B. Zr is almost completely rejected from the α-Fe phase, but some amount of B remains dissolved in the α-Fe phase. The as-quenched alloy is amorphous possibly with the median range order (MRO) structure. Unlike previously published results, no evidence for compositional decomposition prior to the crystallization reaction was found. This suggests that the crystallization progress by the nucleation and growth mechanism, and that redistribution of Zr and B from the crystallized phase to the amorphous matrix controls the grain growth. In fact, during the nucleation and growth stage, enrichment of Zr was found in front of the growing interface of the α-Fe particles, suggesting that the grain growth was controlled by the diffusion of Zr.

  • the microstructure evolution of a fe73 5si13 5b9nb3cu1 nanocrystalline soft Magnetic Material
    Acta Metallurgica Et Materialia, 1992
    Co-Authors: K Hono, Akihisa Inoue, K Hiraga, Q Wang, T Sakurai
    Abstract:

    Abstract The microstructure evolution in the course of crystallization of a splat-quenched Fe73,5Si13.5B9Nb3Cu1 amorphous alloy was investigated by atom probe field ion microscopy (APFIM) and high resolution transmission electron microscopy (HRTEM). All the alloying elements were found to be distributed homogeneously as an amorphous solid solution in the as-quenched state. At an initial stage of annealing, a concentration fluctuation of Cu was found to occur. Cu formed clusters of a few nanometer diameter and their composition was found to be approximately 30 at.% Cu at the beginning. In the later stage, a b.c.c. FeSi solid solution and the B and Nb enriched amorphous phase with the smaller Si content were found to coexist. In addition to these two phases, Cu enriched particles containing approximately 60 at.% Cu were found to be present in the intergranular regions, although we were not successful yet to determine whether this was a crystalline or amorphous phase. Based on these observations, we discuss the crystallization process of this alloy at 550°C which leads to the emergence of excellent soft Magnetic properties.

  • atom probe analysis of fe73 5si13 5b9nb3cu1 nanocrystalline soft Magnetic Material
    Applied Physics Letters, 1991
    Co-Authors: K Hono, A Inoue, T Sakurai
    Abstract:

    The microstructure of Fe73.5Si13.5B9Nb3Cu1 soft Magnetic Material with a nanocrystalline structure has been investigated by atom probe field ion microscopy. In the as‐quenched amorphous sample, all the alloying elements were found to distribute homogeneously as an amorphous solid solution. In the annealed sample with the optimum soft Magnetic properties, we found that two phases were present. One was Fe‐Si solid solution and the other was the B‐ and Nb‐enriched region with less Si content. Although some uncertainty remains regarding Cu, the present result is consistent with an early speculation based on the lattice parameter measurement.

Q Wang - One of the best experts on this subject based on the ideXlab platform.

  • intense milling nanocrystalline fe73 5cu1nb3si13 5b9 a soft Magnetic Material in powdered form
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2000
    Co-Authors: Y Q Qiu, Z J Wang, W Feng, Y D Dong, Xueshan Xiao, Q Wang
    Abstract:

    Abstract The change of structure by intense milling on the nanocrystalline Fe 73.5 Cu 1 Nb 3 Si 13.5 B 9 alloy was investigated. The Magnetic properties of nanocrystalline Fe 73.5 Cu 1 Nb 3 Si 13.5 B 9 dust cores (core of compacted powder) were studied. It was found that the nanostructured ribbons obtained from the crystallization of amorphous state by a proper annealing treatment could be changed into amorphous powder via short time milling. By increasing the milling time, the milled powder return to crystallization. It was also found that the permeability of the nanocrystalline dust cores had nearly not any changes in the frequency range from 1 to 100 kHz. The quality factor Q of the nanocrystalline dust cores increased gradually with increasing frequency. The quality factor Q of nanocrystalline dust cores became higher at the frequency over 50∼70 kHz in comparison with that of the permalloy dust core.

  • the microstructure evolution of a fe73 5si13 5b9nb3cu1 nanocrystalline soft Magnetic Material
    Acta Metallurgica Et Materialia, 1992
    Co-Authors: K Hono, Akihisa Inoue, K Hiraga, Q Wang, T Sakurai
    Abstract:

    Abstract The microstructure evolution in the course of crystallization of a splat-quenched Fe73,5Si13.5B9Nb3Cu1 amorphous alloy was investigated by atom probe field ion microscopy (APFIM) and high resolution transmission electron microscopy (HRTEM). All the alloying elements were found to be distributed homogeneously as an amorphous solid solution in the as-quenched state. At an initial stage of annealing, a concentration fluctuation of Cu was found to occur. Cu formed clusters of a few nanometer diameter and their composition was found to be approximately 30 at.% Cu at the beginning. In the later stage, a b.c.c. FeSi solid solution and the B and Nb enriched amorphous phase with the smaller Si content were found to coexist. In addition to these two phases, Cu enriched particles containing approximately 60 at.% Cu were found to be present in the intergranular regions, although we were not successful yet to determine whether this was a crystalline or amorphous phase. Based on these observations, we discuss the crystallization process of this alloy at 550°C which leads to the emergence of excellent soft Magnetic properties.

T.m. Jahns - One of the best experts on this subject based on the ideXlab platform.

  • application of bi state Magnetic Material to an automotive ipm starter alternator machine
    IEEE Transactions on Energy Conversion, 2005
    Co-Authors: A M Elrefaie, T.m. Jahns
    Abstract:

    A new bi-state soft Magnetic Material has been developed that can have its normally high Magnetic permeability reduced permanently to that of air by means of heat treatment. As a result, localized heating via laser or other means can be used to locally "unmagnetize" regions in machine laminations while retaining the high permeability of adjacent untreated regions. A 6 kW interior permanent magnet (IPM) direct-drive starter/alternator machine was used as the target for this investigation. Two alternative designs for the same set of starter/alternator specifications are presented using the new Magnetic Material for the rotor laminations. Lumped-parameter Magnetic circuit models including saturation were used to design both machines and the electroMagnetic performance results were subsequently confirmed using finite element analysis (FEA). These results indicate that the performance specifications can be met using this new Material while significantly increasing the mechanical integrity of the rotor at high speeds. Advantages and limitations of using this new bi-state Magnetic Material in IPM machine designs for starter/alternators and other applications are discussed.

  • application of bi state Magnetic Material to automotive offset coupled ipm starter alternator machine
    IEEE Industry Applications Society Annual Meeting, 2003
    Co-Authors: A M Elrefaie, R Manzke, T.m. Jahns
    Abstract:

    This paper investigates a new approach to designing high-speed interior permanent-magnet (IPM) synchronous machines using a bi-state soft Magnetic Material. The bi-state Material can have its normally high Magnetic permeability permanently reduced in localized regions to that of air by means of heat treatment. This new work significantly expands a previous investigation by considering offset-coupled IPM machines that make it possible to significantly increase the rotor speed while retaining all of the other specifications of the 6-kW starter/alternator application. Lumped-parameter models, Monte Carlo optimization, and both electroMagnetic and structural finite-element analysis are used to develop new offset-coupled IPM machine designs with the new Material at speeds of 40 000 r/min or higher. Results from this work demonstrate that the bi-state Material offers a promising approach for designing high-speed IPM machines that offer weight and volume advantages compared to their lower speed counterparts at comparable system cost.

Steve Sprague - One of the best experts on this subject based on the ideXlab platform.

  • soft Magnetic Material status and trends in electric machines
    IEEE Transactions on Industrial Electronics, 2017
    Co-Authors: Andreas Krings, Aldo Boglietti, Andrea Cavagnino, Steve Sprague
    Abstract:

    This paper gives an overview on the history and trends of Magnetic Materials used in electrical machines and motors. The presented Materials include silicon–iron, nickel–iron, and cobalt–iron lamination steels, as well as amorphous and nanocrystalline Magnetic Materials and soft Magnetic composites. Development trends and current usage of these selected Materials are presented, giving an outlook on the new Magnetic Material research with regard to electrical machine applications.