Cooling of Permanent Magnet Alloys in a Constant Magnetic Field

Oliver, D. A.; Shedden, J. W.

doi:10.1038/142209a0

Cited by 46 publications

(7 citation statements)

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“…On another front, making use of shape anisotropy of ferromagnets to develop coercivity has been proved to be feasible. The best example may be the Alnico permanent magnets that have been produced since 1930s 4 . In an Alnico magnet, the microstructure is primarily composed of two nanoscale phases formed through Spinodal decomposition: isolated needles of ferromagnetic FeCo-rich phase and a non-magnetic matrix of NiAl-rich phase.…”

mentioning

confidence: 99%

High Energy Product Developed from Cobalt Nanowires

Gandha

Elkins

Poudyal

et al. 2014

Sci Rep

154

114

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Cobalt nanowires with high aspect ratio have been synthesized via a solvothermal chemical process. Based on the shape anisotropy and orientation of the nanowire assemblies, a record high room-temperature coercivity of 10.6 kOe has been measured in Co nanowires with a diameter of about 15 nm and a mean length of 200 nm. As a result, energy product of the wires reaches 44 MGOe. It is discovered that the morphology uniformity of the nanowires is the key to achieving the high coercivity and high energy density. Nanowires of this type are ideal building blocks for future bonded, consolidated and thin film magnets with high energy density and high thermal stability.

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mentioning

confidence: 99%

High Energy Product Developed from Cobalt Nanowires

Gandha

Elkins

Poudyal

et al. 2014

Sci Rep

154

114

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“…Bradley had shown that in the iron-nickel-aluminum alloys certain phases started aggregating in platelets perpendicular to the three cubic ones of the crystal, and at an informal conference held in Manchester the idea was mooted that if cooling took place in a magnetic field the platelets might show a preferred orientation perpendicular to one axis with a consequent greater remanence in this direction. Oliver tried it and found a beneficial effect of about 20 % (Oliver & Shedden, 1938), but this was not judged to be large enough to be commercially interesting. Philips in Holland then added more cobalt, which increased the magnetostriction, and arrived at an alloy in which the effect was several times as great in the preferred direction, so producing permanent magnets of formidable power.…”

Section: Technique For the X-ray Examination Of Crystal Structures Wimentioning

confidence: 99%

`Manchester days'

Bragg¹

1970

Acta Cryst Sect A

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“…[1][2][3] The magnets, which typically contain Fe, Co, Ni, Al, and various additives, have very good overall permanent-magnet properties but suffer from modest coercivities, which are limited to the shape-anisotropy contribution. [4][5][6] Several non-traditional ways to improve alnico magnets have been proposed. Embedded Co nanowires, with a columnar nanostructure similar to anisotropic alnicos, have been considered.…”

Section: Introductionmentioning

confidence: 99%

Coercivity and nanostructure of melt-spun Ti-Fe-Co-B-based alloys

et al. 2016

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Nanocrystalline Ti-Fe-Co-B-based alloys, prepared by melt spinning and subsequent annealing, have been characterized structurally and magnetically. X-ray diffraction and thermomagnetic measurements show that the ribbons consist of tetragonal Ti3(Fe,Co)5B2, FeCo-rich bcc, and NiAl-rich L21 phases; Ti3(Fe,Co)5B2, is a new substitutional alloy series whose end members Ti3Co5B2 and Ti3Fe5B2 have never been investigated magnetically and may not even exist, respectively. Two compositions are considered, namely Ti11+xFe37.5-0.5xCo37.5−0.5xB14 (x = 0, 4) and alnico-like Ti11Fe26Co26Ni10Al11Cu2B14, the latter also containing an L21-type alloy. The volume fraction of the Ti3(Fe,Co)5B2 phase increases with x, which leads to a coercivity increase from 221 Oe for x = 0 to 452 Oe for x = 4. Since the grains are nearly equiaxed, there is little or no shape anisotropy, and the coercivity is largely due to the magnetocrystalline anisotropy of the tetragonal Ti3(Fe,Co)5B2 phase. The alloy containing Ni, Al, and Cu exhibits a magnetization of 10.6 kG and a remanence ratio of 0.59. Our results indicate that magnetocrystalline anisotropy can be introduced in alnico-like magnets, adding to shape anisotropy that may be induced by field annealing.

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Cooling of Permanent Magnet Alloys in a Constant Magnetic Field

Cited by 46 publications

References 1 publication

High Energy Product Developed from Cobalt Nanowires

High Energy Product Developed from Cobalt Nanowires

`Manchester days'

Coercivity and nanostructure of melt-spun Ti-Fe-Co-B-based alloys

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