The Sm-Fe-V based 1:12 bulk magnets

International audienceA bulk magnet based on Sm-Fe-V with the ThMn12 crystal structure has been fabricated for the first time by hot-compaction of mechanically milled powders with a density of 92% of the theoretical density. The isotropic magnet exhibits a maximum coercivity of 1.06 T with a magnetization of 0.59 T, a remanent magnetization of 0.42 T and a (BH)max of 28 kJ m−3 at 3 T applied field. The Curie temperature is found to be 330 °C and the temperature coefficients of remanent magnetization and coercivity are 0.14% C−1 and 0.39% C−1, respectively. Minor hysteresis loops indicate a coercivity mechanism similar to that of the nanocrystalline Nd-Fe-B magnets. The isotropic magnet was hot-deformed up to 75% of its height, and the best magnetic properties obtained were μ0M3T = 0.63 T, μ0Mr = 0.45 T, μ0Hc = 0.88 T and (BH)max = 33 kJ m−3. A small texture perpendicular to compaction direction was detected when the amount of vanadium was reduced, and the deformation temperature was increased from 800 to 1000 °C

Intrinsic magnetic properties of SmFe12−xVx alloys with reduced V-concentration

International audienceIn this work, we present experimental and theoretical results on SmFe 12−x V x (x = 0.5-2.0) alloys with the ThMn 12 (1:12) structure as possible candidates for rare earth-lean permanent magnets. The compound with x = 2 has been previously reported to have a Curie temperature of 330 • C, saturation magnetization of about 80 Am 2 /kg, and anisotropy field around 9 T. We have synthesized the SmFe 11 V compound with a nearly pure 1:12 phase; the x = 0.5 compound couldn't be synthesized. The stability of the x = 1 compound was also confirmed theoretically by calculations of their formation enthalpies using first principles. The newly synthesized SmFe 11 V compound has a Curie temperature of 361 • C and saturation magnetization of 115 Am 2 /kg (1.12 T). The anisotropy field has been obtained in magnetically-oriented fine powders, and is around 11 T. These parameters make SmFe 11 V a good candidate for a new kind of high energy, rare earth-lean permanent magnets

Bulk Mn-Al-C permanent magnets prepared by various techniques

Publisher's PDF.Bulk Mn-Al-C magnets have been prepared by hot-compaction, microwave sintering and hot-deformation. Powders of Mn53.5Al44.5C2 alloy in the ε-phase produced by high energy ball milling have been used as precursor for the hot-compacted and microwave sintered magnets. Hot-deformed magnets were produced from alloy pieces in the τ-phase. The hot-compacted magnet exhibits magnetization, remanence and coercivity of 50 emu/g, 28 emu/g and 3.3 kOe, respectively. Microwave sintered magnet shows a maximum magnetization of 94 emu/g, remanence of 30 emu/g and coercivity of 1.1 kOe. The best magnetic properties are obtained in hot-deformed magnets with magnetization, remanence, coercivity and energy product of 82 emu/g, 50 emu/g, 2.2 kOe and 1.8 MGOe, respectively. Hot-deformed magnets exhibit texture with the highest degree of texture obtained 0.26. It is found that the pressure applied during compaction/deformation favors coercivity.University of Delaware. Department of Physics and Astronomy

Improved soft magnetic properties in nanocrystalline FeCuNbSiB Nanophy ® cores by intense magnetic field annealing

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Synthesis, Properties, and Applications of Multifunctional Magnetic Nanostructures

10.1155/2017/2638715Journal of Nanomaterials2017263871

Structural and magnetic properties of Nd-Fe-Mo-(N) melt-spun ribbons with ThMn12 structure

Figuras descargables en pdf en la página de la editorialThe influence of quenching rate and nitrogenation in melt-spun Nd1.2Fe10.6Mo1.4 has been investigated in terms of microstructure, phase formation and magnetic properties. Increasing the quenching rate leads to smaller grain size. However, it also implies a change in the crystallized phase structure. We obtained a pure ThMn12 (1:12) structure at quenching rates up to 30 m/s, leading to an average grain size of 220 nm. Magnetic measurements of the as-spun ribbons revealed a reduction of the saturation magneti zation for samples quenched above 30 m/s. This is attributed to the formation of a paramagnetic phase and/or magnetic phase with a Curie temperature (TC) close to room temperature which is confirmed by 57Fe Mössbauer spectroscopy. The analysis of the spectra rules out the presence of a ferromagnetic TbCu7 (1:7) phase, which is usually reported in such system. The ribbons were nitrogenated in order to form the harder magnetic phase Nd1.2Fe10.6Mo1.4Nx. The ribbon quenched at 30 m/s with the pure ThMn12 ni tride structure is the optimum sample for getting hard magnetic properties, with a coercivity of 0.6 T, saturation magnetization of 1.15 T and Curie temperature of 350 °C. Finally, we show the good stability of the later phase structure at elevated temperatures (≤ TC), making this compound a good candidate for permanent magnet applications.This work has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No 686056 (NOVAMAG)