Modeling the Heat Treatment of Dy-Diffused Nd₂Fe₁₄B Magnets: The Shell Model

Abstract:

In Nd₂Fe₁₄B sintered magnets there is increase of coercivity after Dy diffusion in the region near the surface of the grains. A kinetical model evaluating the Dy surface diffusion is presented. This model is based on a shell hypothesis: the most relevant place for the nucleation is a tiny shell near the grain boundaries. The kinetical analysis shows that a heat treatment during 1 hour at 850°C is able to produce a Dy-rich layer on the surface of the Nd₂Fe₁₄B grains.

• Periodical: Materials Science Forum (Volumes 727-728)
• Pages: 146-150
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.727-728.146
• Online since: August 2012
• Authors: Marcos Flavio de Campos, José Adilson de Castro
• Keywords: Coercivity, Diffusion, Dysprosium, Grain Size

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