Characterization of the microstructure and corrosion performance of Ce-alloyed Nd-Fe-B magnets

Elisa Isotahdon, Elina Huttunen-Saarivirta, Veli-Tapani Kuokkala

    Research output: Contribution to journalArticleScientificpeer-review

    15 Citations (Scopus)

    Abstract

    Expensive rare-earth elements used in neodymium-iron-boron permanent magnets can be partly replaced by a more abundant cerium without significantly compromising the magnetic properties. In this study, we investigated the effects that cerium addition has on the corrosion resistance of Nd-Fe-B magnets. The cerium-alloyed magnet grade was compared to two Ce-free magnet materials, a standard-grade Nd-Fe-B and a Co-alloyed magnet grade, with respect to microstructure and corrosion behaviour. The microstructure of the magnets was characterized by scanning electron microscopy, with the location of Ce being of primary interest. The magnets were exposed to electrochemical measurements and accelerated corrosion tests. Although the amount of the corrosion-sensitive grain-boundary phase was higher in the Ce-alloyed magnets than in the other two magnet grades, the overall corrosion behaviour was in many ways comparable to that of the Co-alloyed grade magnet, e.g., showing a slight increase in open circuit potential as compared to the standard grade magnet. In accelerated tests, corrosion of the Fe-rich phase was equal to the other magnet grades. Pulverization of the Ce-alloyed magnet was not detected during the accelerated tests, similarly to the Co-alloyed grade.
    Original languageEnglish
    Pages (from-to)190-197
    Number of pages8
    JournalJournal of Alloys and Compounds
    Volume692
    DOIs
    Publication statusPublished - 2017
    MoE publication typeA1 Journal article-refereed

    Fingerprint

    Magnets
    Corrosion
    Microstructure
    Cerium
    Neodymium
    Boron
    Rare earth elements
    Permanent magnets
    Corrosion resistance
    Magnetic properties
    Grain boundaries
    Iron
    Scanning electron microscopy
    Networks (circuits)

    Keywords

    • Rare earth alloys and compounds
    • Corrosion
    • Scanning electron microscopy
    • SEM
    • Electrochemical impedance spectroscopy

    Cite this

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    abstract = "Expensive rare-earth elements used in neodymium-iron-boron permanent magnets can be partly replaced by a more abundant cerium without significantly compromising the magnetic properties. In this study, we investigated the effects that cerium addition has on the corrosion resistance of Nd-Fe-B magnets. The cerium-alloyed magnet grade was compared to two Ce-free magnet materials, a standard-grade Nd-Fe-B and a Co-alloyed magnet grade, with respect to microstructure and corrosion behaviour. The microstructure of the magnets was characterized by scanning electron microscopy, with the location of Ce being of primary interest. The magnets were exposed to electrochemical measurements and accelerated corrosion tests. Although the amount of the corrosion-sensitive grain-boundary phase was higher in the Ce-alloyed magnets than in the other two magnet grades, the overall corrosion behaviour was in many ways comparable to that of the Co-alloyed grade magnet, e.g., showing a slight increase in open circuit potential as compared to the standard grade magnet. In accelerated tests, corrosion of the Fe-rich phase was equal to the other magnet grades. Pulverization of the Ce-alloyed magnet was not detected during the accelerated tests, similarly to the Co-alloyed grade.",
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    Characterization of the microstructure and corrosion performance of Ce-alloyed Nd-Fe-B magnets. / Isotahdon, Elisa; Huttunen-Saarivirta, Elina; Kuokkala, Veli-Tapani.

    In: Journal of Alloys and Compounds, Vol. 692, 2017, p. 190-197.

    Research output: Contribution to journalArticleScientificpeer-review

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