Development of Magnetic Losses During Accelerated Corrosion Tests for Nd-Fe-B Magnets Used in Permanent Magnet Generators

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

    Research output: Contribution to journalArticleScientificpeer-review

    2 Citations (Scopus)


    Sintered Nd-Fe-B magnets are critical components in permanent magnet wind generators. They are the strongest permanent magnets available and thus enable the construction of light and effective devices, but their stability in corrosive environments is limited. In this work, the formation of corrosion losses in two types of Nd-Fe-B alloys was studied. Magnets were in a magnetized state during the corrosion test, enabling monitoring of the development of losses in magnetic flux along with those in weight. Parallel flux and weight loss measurements conducted during corrosion tests showed that percentage weight losses were lower than the total flux losses. Scanning electron microscope studies of corroded specimens disclosed that the magnets first underwent dissolution of the grain-boundary phase, followed by the detachment and movement of the loosened grains in the magnetic field. The degradation was accelerated by oxidation of the matrix phase, which introduced further damage by volume expansion.

    Original languageEnglish
    Pages (from-to)732-741
    Number of pages10
    Issue number6
    Publication statusPublished - 1 Jun 2016
    Publication typeA1 Journal article-refereed


    • Corrosion
    • Corrosion losses
    • Highly accelerated stress test (HAST test)
    • Improved corrosion resistance sintered Nd-Fe-B magnets
    • Improved stability sintered Nd-Fe-B magnets
    • Nd-Fe-B
    • Permanent magnet
    • Scanning electron microscopy
    • Thermal losses
    • Wind power

    Publication forum classification

    • Publication forum level 2

    ASJC Scopus subject areas

    • General Materials Science
    • General Chemical Engineering
    • General Chemistry


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