Permanent magnet materials—Developments during the past 12 months

Stadelmaier, H. H.; Henig, Ernst-Theo

doi:10.1007/bf02648614

Cited by 6 publications

(1 citation statement)

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“…It is found that the Co 80 Zr 18 B 2 alloy ribbons, which are fabricated by using a rapid quenching method and consequently annealing, could have a coercivity (H c ) as high as of 4.4 kOe and maximum energy product (BH) max of 4.7 MGOe [7]. These hard magnetic properties in these alloys are attributed to the Co 11 Zr 2 and Co 5 Zr phases [6,[8][9][10][11][12][13][14][15][16][17]. There are several approaches to enhance the coercivity of Co-Zr based alloys, such as adding metallic elecments (Ti, Si or Mo) to facilitate the formation of the hard-magnetic phases and decrease both the grain size and the fraction of the soft magnetic phase of Co [18][19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

INVESTIGATION OF FABRICATION OF Co-Zr BASED RARE EARTH-FREE HARD MAGNETIC ALLOYS BY MELT-SPINNING METHOD

Duong¹

2018

JST

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Co-Zr based alloy has attracted much interest of potential to replace the rare earth-containing hard magnetic materials due to its high coercivity. In this study, we investigated the effects of subtituting elements of M (Ti, Si and Nb) and annealing temperature on the structure and magnetic properties of Co79-xZr18+x-yMyB3 alloy ribbons (x = 0 - 2, y = 0 - 4). The alloy ribbons with a thickness of 20 µm were prepared by melt-spinning method with a rolling speed of 40 ms-1. A part of the melt-spun ribbons was annealed at different temperatures from 550 to 800 oC for various durations from 2 to 15 minutes. Their structure and magnetic properties were investigated by X-ray diffraction (XRD) and a pulsed field magnetometer (PFM), respectively. The results of the XRD analysis showed that two soft magnetic phases, namely Co and Co23Zr6, coexist with a Co5Zr hard magnetic phase in the alloy ribbons. The fraction of these phases was changed with both the concentration of the subtituting elements and annealing process. Hard magnetic properties of the alloy ribbons can be strengthened significantly, namely a large coercivity Hc > 4 kOe and maximum energy product (BH)max > 3.5 MGOe were obtained with an appropriate concentration of Ti, Si or Nb and annealing process. Furthermore, the subtituting elements also affect the optimal annealing temperature for these alloys. The obtained strong hard magnetic parameters of these rare earth-free alloys are of great importance in pratical application.

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Section: Introductionmentioning

confidence: 99%

INVESTIGATION OF FABRICATION OF Co-Zr BASED RARE EARTH-FREE HARD MAGNETIC ALLOYS BY MELT-SPINNING METHOD

Duong¹

2018

JST

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Magnetic Materials, Bulk

Wernick¹

2000

Kirk-Othmer Encyclopedia of Chemical Technology

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Magnetism is classified according to the nature of the bulk magnetic response in a magnetic field. Types of magnetism are defined as are the terms of magnetic behavior. Bulk magnetic materials may be classified as either soft or hard. The important soft magnetic materials, characterized by high permeability and low coercivity, include iron and low carbon steel, iron–silicon alloys, iron–aluminum and iron–aluminum–silicon alloys, cobalt–iron (Permendurs) and nickel–iron alloys (Permalloys), ferrites, and amorphous magnetic alloys. The iron‐based alloys are used for power distribution transformers and magnetic shielding. The ferrites are used at high frequencies for inductors and communication transformers as well as for microwave devices. Moreover, the use of MnZn ferrite cores in power transformers is increasing rapidly. The hard of permanent magnet materials are characterized by high coercivity and high energy product. Materials in use include the hexagonal barium and strontium ferrites, alnicos, the modified binary cobalt‐base intermetallics containing rare earths, and the ternary neodynium iron‐base intermetallics. Motors, loudspeakers, and disk drives are the largest consumers of hard magnetic materials. The exceptionally large values of maximum energy products and coercivities of the Nd–Fe–B magnets permit use in devices where small size and superior performance are desired. Many of the semihard permanent magnet materials are sufficiently ductile for forming into requisite shapes. Information is presented for several important materials which can be cold formed, rolled to thin foil, and can be stamped into precision parts at high speeds.

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