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Radiation Effects in Rare-Earth Permanent Magnets

  • J. R. Cost (a1), R. D. Brown (a1), A. L. Giorgi (a1) and J. T. Stanley (a2)


Nd-Fe-B and Sm-Co permanent magnets have been irradiated with fission neutrons and gamma rays. Irradiated samples were periodically removed for room temperature measurements of the open-circuit remanence. Hysteresis loops were measured before and after irradiation. For neutron irradiation, two Nd-Fe-B magnets showed a rapid loss of remanence, while a third magnet from another manufacturer decayed more slowly, suggesting that the radiation hardness of Nd-Fe-B magnets may depend on microstructural details. Irradiation in the Omega West Reactor at Los Alamos with fast neutrons caused the fast-decay samples to have an Wtial loss of remanence of 1% for irradiation at 350 K to a fluence of 1015 n/cm2. Both SmCo5 and Sm2Co17 magnets showed excellent resistance to radiatifg-induied loss of remanence for neutron irradiation to a fluence of 2.6×1018 n/cm2. Results for gamma radiation showed no loss of remanence for a dose of about 49 Mrad using a 60Co source. Possible mechanisms for radiation-induced loss of magnetic properties are discussed.



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Radiation Effects in Rare-Earth Permanent Magnets

  • J. R. Cost (a1), R. D. Brown (a1), A. L. Giorgi (a1) and J. T. Stanley (a2)


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