کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
7880917 | 1509593 | 2015 | 8 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Temperature-dependent Dy diffusion processes in Nd-Fe-B permanent magnets
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
مهندسی مواد
سرامیک و کامپوزیت
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چکیده انگلیسی
Nd-Fe-B permanent magnets have been coated with 0.6 wt.% dysprosium and annealed at various temperatures to study the impact of the temperature-dependent Dy diffusion processes on both the magnetic properties and the microstructure. When optimum annealing conditions are applied the Dy processed magnets with initial coercivity of â¼1100 kA mâ1 yield coercivity increases which can exceed 400 kA mâ1 without a significant reduction of the remanent magnetic polarization. The improved stability against opposing magnetic fields can be observed up to a depth of â¼3 mm along the diffusion direction, restricting the application of the Dy diffusion process to either thin magnets or magnets with tailored coercivity gradients. While in the proximity of the Dy-coated surface, each grain has a Dy-enriched shell with a Dy content of â¼6 at.%; the Dy concentration decreases exponentially to â¼1.8 at.% after a diffusion depth of 400 μm and to â¼1 at.% after a diffusion depth of 1500 μm, as was found with wavelength dispersive X-ray spectroscopy and scanning transmission electron microscopy-energy dispersive X-ray spectroscopy, respectively. In the vicinity of the Dy-coated surface, the mechanism of the Dy-shell formation is attributed to the melting/solidification of a heavy-rare-earth-rich intermediate phase during high-temperature annealing. This is based on the observation that a constant Dy concentration over the width of the shells was found. Also an epitaxial relation between the Dy-poor core and the Dy-rich shell was observed by electron backscattered diffraction, which is supported by results obtained with Kerr microscopy.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Acta Materialia - Volume 83, 15 January 2015, Pages 248-255
Journal: Acta Materialia - Volume 83, 15 January 2015, Pages 248-255
نویسندگان
K. Löewe, C. Brombacher, M. Katter, O. Gutfleisch,