Correlation of microstructure and magnetic properties in Sm(CobalFe0.1Cu0.1Zr0.033)6.93 magnets solution-treated at different temperatures

Xu, Cheng; Wang, Hui; Zhang, Tian-Li; Попов, А. Г.; Gopalan, R.; Jiang, Chengbao

doi:10.1007/s12598-018-1182-z

Cited by 29 publications

(2 citation statements)

References 39 publications

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“…For Magnet B, the solution temperature is higher than for Magnet A. According to the phase diagram, for Magnet A at the optimized solution temperature, the 1:7H phase is formed during the solid solution process; this is then followed by further aging treatment and the 1:7H phase evolves a complete cellular structure . However, for Magnet B treated at a higher solution temperature, besides the main 1:7H phase, the 2:17H phase also forms, and after aging, the 2:17H phase transforms to an incomplete cellular structure due to the lower Cu and Sm content, which is consistent with our energy dispersive spectrometer (EDS) composition analysis.…”

Section: Discussionmentioning

confidence: 99%

Initial Irreversible Losses and Enhanced High‐Temperature Performance of Rare‐Earth Permanent Magnets

Xia

Huang

et al. 2019

Adv Funct Materials

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There is an increasing demand for permanent magnets with high-temperature stability. Normally, the magnets are heat treated above the operating temperature range to saturate the irreversible losses, thereby producing magnets that are stable, but with significantly degraded performance. In addition, uncertainty about the losses in differently shaped magnets causes difficulties for efficient magnetic circuit design. The variation of the initial irreversible losses with magnet shape, hysteresis loop, and operating temperature is presented here. Losses are not associated with thermal demagnetization of the whole magnet, but the damage is concentrated in an outer surface "skin" at the pole surfaces, where the demagnetizing field is nonuniform. The initial irreversible remanence loss at room temperature / r r r r M M M M ∆ ∆ ′ ′can be predicted as the product of the slope of the high-temperature magnetization curve k(T) and the effective demagnetizing factor N . Heat treatment with the vulnerable surfaces in contact with soft iron slabs moves the skin out of the permanent magnet and reduces the irreversible remanence loss by 30% or more, potentially improving the performance of permanent-magnet motors, generators, bearings, and thrusters. The results deepen the understanding of the magnetism of irreversible losses and will guide the applications of permanent magnets at higher temperatures.

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Section: Discussionmentioning

confidence: 99%

Initial Irreversible Losses and Enhanced High‐Temperature Performance of Rare‐Earth Permanent Magnets

Xia

Huang

et al. 2019

Adv Funct Materials

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“…Спеченные магниты Co-25%Sm имеют мелкое (около 8 мкм) зерно, что обеспечивает высокую коэрцитивность. Они также обладают хорошо выровненной (00l) ориентационной текстурой [8]. Интерметаллические соединения SmCo 5 , Sm 2 Co 17 , Zr 5 Co 3 FeSm хрупкие и могут разрушаться при механической обработке даже с помощью электроэрозионного инструмента [9].…”

Section: Introductionunclassified

Magnetic structure of Co–25%Sm sintered magnets after electrical discharge machining

Slinkin

Чикова

2020

Izv.VUZ. Tsvet. Met.

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Scanning electron microscopy and magnetic force microscopy were used to conduct the metallographic study of the surface microstructure of KS25 grade Co–25%Sm sintered rare-earth magnets after Electrical Discharge Machining (EDM). The chemical composition of the studied samples: Sm – 25 wt.%; Fe – 18 wt.%; Cu – 5 wt.%; Zr – 3 wt.%; Co – the rest. One of the sample surfaces was subjected to EDM in various ways with changes in such EDM parameters as the straight-line processing speed and offset. The microstructure of magnets contains four coexisting phases: SmCo5, Sm2Co17, Zr5Co3FeSm and Sm2O3. The grain size is 10–50 μm. Crystals of the Zr5Co3FeSm intermetallic compound are 1–5 μm in size, and globular inclusions of Sm2O3 samarium oxide are 2–10 μm. EDM affected the thickness and chemical composition of the defective layer. In general, the chemical composition varies slightly in the direction from the defective layer inward the sample: the content of Sm, Cu, O, and Zr decreases; the content of Fe and Co increases. At a distance of 500 μm from the defective layer inwards the sample, the grain size increases by 40–50 %, while the porosity decreases. At the same time, the size of Sm2O3 oxides slightly increases. The study of the magnetic structure on surfaces perpendicular to the axis of magnetization by means of magnetic force microscopy revealed the presence of a complex domain structure of grains in the form of a labyrinth with a domain size of ~3÷5 μm. Separate singledomain grains ~30÷50 μm in size were also found. Due to the material heating and oxidation, EDM promotes the domain structure of grains appearing in the form of a labyrinth instead of single-domain grains, and the SmCo5 → Sm2Co17 phase transition, which causes a decrease in coercive force.

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Low remanence temperature coefficient Sm1−xErx(Co, Fe, Cu, Zr)z magnets operating up to 400 °C

Zhang

Wang

et al. 2019

Rare Met.

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Correlation of microstructure and magnetic properties in Sm(CobalFe0.1Cu0.1Zr0.033)6.93 magnets solution-treated at different temperatures

Cited by 29 publications

References 39 publications

Initial Irreversible Losses and Enhanced High‐Temperature Performance of Rare‐Earth Permanent Magnets

Initial Irreversible Losses and Enhanced High‐Temperature Performance of Rare‐Earth Permanent Magnets

Magnetic structure of Co–25%Sm sintered magnets after electrical discharge machining

Low remanence temperature coefficient Sm1−xErx(Co, Fe, Cu, Zr)z magnets operating up to 400 °C

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