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Yekaterinburg, Russia

Popov A.G.,RAS Institute of Metal Physics | Kudrevatykh N.B.,Ural Federal University | Vyatkin V.P.,NPP NeoMag | Vasilenko D.Y.,NPP NeoMag | And 3 more authors.
Physics of Metals and Metallography | Year: 2010

The microstructure of platelike Nd-Fe-B alloys prepared by rapid quenching from the melt, namely, by the strip casting technique, has been studied. The processes of grain refinement, texture formation, and sintering were optimized. It is shown that the maximum energy product (BH) max ≥ 50 MGOe can be realized in sintered magnets prepared from the alloy with 29 wt % Nd after a two-step heat treatment. The oxygen content in such magnets does not exceed 0.3 wt %; the degree of texture is α t = 0.95. Copyright © 2010 Pleiades Publishing, Ltd. Source


Popov A.G.,RAS Institute of Metal Physics | Vasilenko D.Yu.,NPP NeoMag | Puzanova T.Z.,RAS Institute of Metal Physics | Shitov A.V.,RAS Institute of Metal Physics | Vlasyuga A.V.,NPP NeoMag
Physics of Metals and Metallography | Year: 2011

Effect of diffusion annealing on the formation of dysprosium-saturated grain boundaries in sintered Nd-Fe-B magnets has been studied. As a source of diffusion, we used powders of metallic dysprosium, DyCu, DyGa, and Dy 3Co alloys and DyH x hydride. Plates ∼1 mm thick made of sintered magnets were molded into powders with a particle size from 3 to 500 μm and subsequently annealed in a vacuum at 750-850°C for 0.5-10 h. After annealing, the microstructure and the elemental composition of grains and grain boundaries were studied by scanning electron microscopy. Under optimum annealing conditions, Dy atoms were shown to diffuse preferentially through grain boundaries of the magnets. The coercive force H c of Nd-Fe-B plates, which were annealed in contact with the DyGa, Dy 3Co and DyH x powders and subsequently annealed at 550°C, increases by 4-6 Oe; no substantial decrease in the remanence takes place. The increase in the coercive force depends of the powder particle size and temperature and time of diffusion annealing. © 2011 Pleiades Publishing, Ltd. Source

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