A magnetic bubble domain flight recorder

Chen, T.; Bohning, O. D.; Tocci, L.; Archer, J. L.; Stermer, R. L.

doi:10.1109/tmag.1974.1058497

Cited by 9 publications

(1 citation statement)

References 7 publications

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“…MnBi-based alloys are considered an attractive alternative as precursor materials for designing permanent magnets due to the formation of the Low Temperature Intermetallic Phase (LTIP)-MnBi, which is a ferromagnetic phase with a NiAstype hexagonal structure and spatial group P6 3 /mmc. The uniaxial magnetocrystalline anisotropy of this phase possesses a magnetocrystalline anisotropy constant (K 1 ) as high as 0.90 × 10 6 J/m 3 together with a saturation magnetization (µ 0 M s ) of 0.73 T [1][2] as well as a positive temperature coefficient of coercivity [3][4][5][6], which enables these alloys for potential applications in permanent magnets capable to operate at high temperatures [7]. An additional feature of these MnBi alloys is their rare-earth free content, which will represent a competitive advantage in terms of cost for production relative to the well established Nd-Fe-B alloys for supermagnets production.…”

Section: Introductionmentioning

confidence: 99%

Coercivity mechanism of rare-earth free MnBi hard magnetic alloys

Zamora¹,

Betancourt²,

Figueroa³

2018

Rev. Mex. Fís.

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In this work, we present and discuss results concerning the hard magnetic behavior of rare earth-free MnBi alloys obtained by suction casting technique. The physics of coercivity for these type of alloys is based on the nucleation process of reverse domains, which in turn is determined by the alloy microstructure features such as phase distribution, morphology, grain size and in particular, defects, which are characteristic of real materials. The microstructure of the as-cast alloy presented here comprises the formation of the Low Temperature Intermetallic Phase (LTIP)-MnBi, interspersed within Bi-and Mn-rich areas. A considerable intrinsic coercivity field of 238 kA/m together with a saturation magnetization of 0.04 T were observed. The nucleation controlled mechanism of this alloy was described in terms of the Kronmüller equation, which incorporates the detrimental effect of microstructure defects through fitting parameters associated to reduced intrinsic magnetic properties at grain size boundaries, interfaces and local demagnetizing fields. A notorious switching of coercivity mechanism associated with domain wall pinning was found to be produced upon annealing of the alloy at 583 K for 24 hrs, yielding a drastic reduction of coercivity (down to 16 kA/m). The key microstructural feature determining the switching of coercivity mechanism is the formation/suppression of Bi-rich areas, which promotes the nucleation and growth of LTIP.

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Section: Introductionmentioning

confidence: 99%