Effects of electron - beam and y - ray irradiation on the magnetic flux of Nd - Fe - B and Sm - Co permanent magnets

The effects of irradiation with 17 MeV electron beams and “‘Co y-rays on the magnetic flux of Nd-Fe-B and Sm-Co permanent magnets have been studied. At an electron dose of 2.1 X 10d3 C/cm’ (at an absorbed dose of 2.6 MGy), the magnetic flux loss of Nd-Fe-B is 9%, while the flux loss of Sm-Co is below 0.4% at a dose of 1.4 X 10B3 C/cm’. After remagnetization of the irradiated Nd-Fe-B sample the magnetic flux almost recovers to the strength before irradiation. For y-ray irradiation of Nd-Fe-B and Sm-Co at an absorbed dose of 2.8 MGy, the flux loss is below 0.5%. Irradiation by y-rays is considered to be equivalent to that of electrons at energies below 0.8 MeV. The difference between the results for electron-beam and y-ray irradiation of Nd-Fe-B is discussed. . .