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概述了锰在永磁材料中的应用,其主要为Fe-Mn系永磁合金、Mn-Al系永磁合金、Mn-Bi系永磁合金、稀土锰基化合物、永磁薄膜以及Mn在永磁材料中的掺杂。 相似文献
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In this article, we report the microstructural evolution of rapidly solidified Sm-Co alloys from 4 to 16 at. pct Sm. We have
observed a wide variety of phase formation and microstructures, ranging from primary Co dendrite formation to eutectic structures
to the formation of the metastable SmCo7 compound. In particular, we observed nonequilibrium formation of Co along with SmCo7, whose presence caused a decrease in coercivity from ∼10 kOe to 500 Oe. Alloying elements reduced the scale of the microstructure,
effectively offsetting the detrimental effects of the Co phase formation and leading to a recovery of the coercivity. The
eutectic structure with Co rods surrounded by SmCo7 provides a natural path to nanoscale hard/soft magnetic nanocomposites, where control of scale and phase content is critical.
This article is based on a presentation made in the symposium entitled “Phase Transformations in Magnetic Materials”, which
occurred during the TMS Annual Meeting, March 12–16, 2006, in San Antonio, Texas, under the auspices of the Joint TMS/MPMD
and ASMI-MSCTS Phase Transformations Committee.
相似文献
J.E. SHIELD (Associate Professor)Email: |
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《钢铁研究学报(英文版)》2006
High-quality permanent magnets either are based on large nucleation fields or strong pinning forces of domain walls (dws). In the case of 2:17 based magnets depending on the temperature range considered both hardening mechanisms have been discussed. The dominant hardening mechanisms at temperatures below around 700 K are repulsive or attractive pinning of domain walls at the cell walls (1:5 structure) between the nanostructured pyramidal cells (2:17 structure). Micromagnetic calculations of the pinning forces sensitively depend on the shape of the interaction potential between the dw and the microstructure. In the case of the 2:17 based magnets these calculations become rather complex if the domain wall width is of the order of the potential width. In this case the domain wall is modified due to the space dependent local anisotropy which changes from K12:17 to K11:5 of the cell boundary phase over a distance D of the intergranular phase boundary. Using the K1(r)-profiles as determined from the chemical composition obtained by high-resolution EDX measurements the coercive field due to domain wall pinning is determined self-consistently as a function of the pinning-potential parameters taking into account the modification of the domain wall by the space dependent material parameters. It is shown that the coercive field of the high-temperature magnets as a function of the width of the cell boundary phase varies between 3 T for a sharp boundary (D = 0 nm) and 1 T for a wide boundary (D = 4 nm). On the basis of micromagnetism the condition for the dominance of pinning or nucleation is investigated. It is shown that in the case of 2:17 based high-temperature magnets with increasing temperature the hardening mechanisms change from repulsive to attractive pinning and nucleation starts at around 700 K. The temperature ranges where the transitions take place sensitively depend on the Cu content and on the annealing parameters. 相似文献
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Metallurgist - A requirement for improving powder metallurgy technology of alloys for permanent magnets containing rare-earth metals based on the use of secondary resources and a replacement of... 相似文献
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Study on Key Techniques for Producing High Performance NdFeB Sintered Permanent Magnets 总被引:2,自引:0,他引:2
NdFeBmagnetshavebeenimproveddra maticallysinceitwasinventedin 1 983 .Twotypesofsinteredmagnets ,highenergyprod ucts ((BH ) max)anddoublehigh (high(BH ) maxandhighcoercivity (iHc) )arethetwotendenciesforNdFeBsinteredmagnets .Bothfactoriesandresearchinstitutesarefocus… 相似文献
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《钢铁研究学报(英文版)》2006
This paper presents a new multi-disc coreless permanent magnet synchronous motor whose permanent magnets are arranged in the “Halbach array”. Unit motor combined structure is adopted to simplify processing technology of the motor. Airgap magnetic flux density is increased taking advantage of high remanence and coercive force of NdFeB permanent magnet material and high gathering magnetism function of Halbach array. This also makes coreless motor possible. The structure and the characteristics of the motor using Halbach array are also introduced. The FEM analysis has been done to build the mathematical model and study the magnetic field characteristics of the motor. And finally the interrelated design parameters of permanent magnet and arrangement between unit motors are determined according to the results of die FEM analysis. 相似文献
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林河成 《有色金属材料与工程》2006,27(4):33-37
综述了我国烧结钕铁硼永磁材料的生产、应用和市场的发展现状。目前这种永磁体的生产量、国内用量及国内外市场销量都居世界之冠,其发展前景仍然看好。针对存在的问题提出了建议。 相似文献
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《钢铁研究学报(英文版)》2006
In present study, sintered Nd-Fe-B permanent magnets with different compositions were fabricated by using both Spark Plasma Sintering (SPS) technique and conventional sintering technique. Microstructure and compositions of both magnets are observed by scanning electron microscope with energy dispersive X-ray detector. Magnetic properties, mechanical properties, and chemical stabilities of both Nd-Fe-B magnets are investigated. Compared with the conventional sintered magnets, SPS Nd-Fe-B magnets possess comparable magnetic properties, better corrosion resistance and mechanical properties. Further investigation shows that the good all-around properties of the SPS magnets result from their unique microstructure. In detail, the grain size of Nd2Fe14B main phase is fine and uniform, only a few Nd-rich phase forms along the grain boundaries of Nd2Fe14B, while most of them agglomerates into the triple junctions. As a result, SPS process is expected to be a promising method for the production of new Nd-Fe-B magnets with good all-around properties. 相似文献
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《钢铁研究学报(英文版)》2006
Various systems, which are composed of rare-earth permanent magnets and generate strong magnetic fields, are calculated. Strong fields are taken to mean the fields with the strength, which exceeds the magnet induction. Calculated values of the strength of strong fields can mount to 20–150 kOe. Depending on form of domains where this fields are localized they can be classified as linear and point fields, the corresponding systems can be named linear and point as well. It was shown that the maximal linear field can be obtained in Halbach cylinder (prism), in which this field tends to Hx = 4πMs ln(a/x) with increasing of number of component sectors. The maximal point field is reached in systems composed of many conical magnets, divided by many sectors. The strength of such field tends to the value Hx = 8πMs ln(a/x). Experimental values of strong fields measured in some systems by various methods are in good agreement with calculated data. 相似文献