Radiation damage of materials due to high-energy ion irradiation

Abstract The radiation damage of the Nd–Fe–B magnets irradiated by 200 MeV protons was investigated over the dose range from ∼102 to ∼2×105 Gy at Wakasa-wan Multi-purpose Accelerator with Synchrotron and Tandem (W-MAST). The magnetic flux of Nd–Fe–B magnets decreased drastically as the proton dose increased. Increase of permeance coefficient as well as of coercive force led to the enhancement of the resistance of Nd–Fe–B magnets to the radiation-induced damage. The demagnetized magnets can be fully magnetized again to the same intensity as before the irradiation. The aluminum nitride (AlN) layers produced by 190 keV N+ implantation of Al contained the defect, which was derived indirectly from the oxygen concentration. In very high dose of more than ∼1019 ions/cm2, the rearrangement of the defect might occur due to the radiation-induced collisions.