Defect structure and magnetic properties of MnAl permanent magnet materials

Landuyt, J. Van; Tendeloo, Gustaaf Van; Broek, J.J. van den; Donkersloot, H. C.; Zijlstra, H.

doi:10.1109/tmag.1978.1059949

Cited by 51 publications

(13 citation statements)

References 5 publications

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“…In contrast, the MM Mn 54 Al 46 sample has much higher H C than the bulk sample due to the small t-phase grain size. The increased H C maybe also due to the domain wall pinning action of the large amount of antiphase boundaries [40,44] or the precipitation of b and g 2 -phase at the expense of lowering M S [45].…”

Section: Article In Pressmentioning

confidence: 99%

Structural and magnetic properties of nanostructured Mn–Al–C magnetic materials

Zhang

Baker

Cui

et al. 2007

Journal of Magnetism and Magnetic Materials

148

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Section: Article In Pressmentioning

confidence: 99%

Structural and magnetic properties of nanostructured Mn–Al–C magnetic materials

Zhang

Baker

Cui

et al. 2007

Journal of Magnetism and Magnetic Materials

148

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“…[15,16] The microstructure is highly sensitive to the metallurgical state of the material. APBs are observed after the phase formation but are absent in hot deformed magnets [12] and the population of 2 of the 3 different twin-like defects is remarkably reduced in the hot deformed state. [14] In the initial material, after the formation of the τ phase the coercivity is comparably low, which has been attributed to the presence of APBs.…”

Section: Introductionmentioning

confidence: 99%

Role of twin and anti-phase defects in MnAl permanent magnets

et al. 2017

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We quantify and explain the effects of both anti-phase boundaries and twin defects in as-transformed τ -MnAl by carrying out micromagnetic simulations based closely on the results of microstructural characterization. We demonstrate that magnetic domain walls nucleate readily at anti-phase boundaries and are strongly pinned by them, due to antiferromagnetic coupling. Likewise, twin boundaries reduce the external field required to nucleate domain walls and provide strong pinning potentials, with the pinning strength dependent on the twinning angle. The relative strengths of the known twin defect types are quantified based on the anisotropy angles across their boundaries. Samples that have undergone heat treatment are imaged using electron back-scatter diffraction. The precise crystallographic orientation is mapped spatially and converted into a number of realistic finite element models, which are used to compute the effects of large concentrations of twin domains in a realistic morphology. This is shown to have a negative effect on the remanence coercivity and squareness. The maximum energy product (BH) max is therefore significantly lower than the theoretical limit of the material and much lower than MnAl permanent magnets that have been further processed to remove twin defects. The knowledge gained in this study will allow the optimization of processing routes in order to develop permanent magnets with enhanced magnetic properties.

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“…1 shows the binary phase diagram of Fe-Pd [3]. The need to quench samples from solid solution is not unique to the Fe-Pd system, and is considered imperative for obtaining high-quality properties in other systems such as FSMA Ni 2 FeAl, high magnetostriction Fe-Ga, and the hard magnet MnAl [4][5][6]. In bulk systems, this is readily accomplished by encapsulating the sample in a quartz ampoule during annealing and then shattering the ampoule during the quench.…”

Section: Introductionmentioning

confidence: 99%