The Samarium Depleted Zone in SmCo5 Magnets

Marcos Flavio de Campos; F.J.G. Landgraf

doi:10.4028/www.scientific.net/MSF.727-728.169

Paper Titles

Modeling the Heat Treatment of Dy-Diffused Nd₂Fe₁₄B Magnets: The Shell Model
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Nucleus Size Determination for Nd₂Fe₁₄B, Sm₂Co₁₇, SmCo₅ and BaFe₁₂O₁₉ Magnets
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A General Coercivity Model for Soft Magnetic Materials
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Diffusion Coefficients of Interest for the Simulation of Heat Treatment in Rare-Earth Transition Metal Magnets
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The Samarium Depleted Zone in SmCo₅ Magnets
p.169

Modeling the Densification of FeSi Sintered Magnetic Alloys
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Thermal Aging of Reprocessed NdFeB Powders
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Adhesion Tests in Quasicrystal Powders Reinforced Geopolymer Composites
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Study of Obtainment of NiCrAlC Alloys by High Energy Ball Milling
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HomeMaterials Science ForumMaterials Science Forum Vols. 727-728The Samarium Depleted Zone in SmCo5 Magnets

The Samarium Depleted Zone in SmCo₅ Magnets

Abstract:

After sintering, SmCo₅ magnets may present a surface layer depleted in Samarium. This happens because Samarium is much more susceptible for oxidation than cobalt. Besides, samarium has high vapour pressure. This Sm depleted zone is of the order of ~ 1 mm (in a 10 mm diameter magnet), and present oxygen content 1000 ppm higher than the center of the magnet. This layer is composed by SmCo_(5+x), which presents low coercivity (1-2 kOe). The occurrence of the Sm depleted layer is associated with kinks in the 2^nd quadrant of the hysteresis curve. After the removal of this layer, the hysteresis kinks disappear. The efficacy of different chemical etchings (Nital and chromic acid) to reveal microstructural constituents was discussed in detail. Nital is recommended for observation of magnetic domains under polarized light (Kerr effect), whereas chromic acid is more suitable to identify Sm₂Co₇ and other high Sm phases.

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Materials Science Forum (Volumes 727-728)

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169-174

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https://doi.org/10.4028/www.scientific.net/MSF.727-728.169

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August 2012

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Marcos Flavio de Campos, F.J.G. Landgraf

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Heat Treatment, Magnets, Sintering, SmCo

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