Study on Irradiation Effect of FeCrCo and NdFeB Permanent Magnet Materials

　　Study on Irradiation Effect of FeCrCo and NdFeB Permanent Magnet Materials
　　Damage behaviors of FeCrCo alloy irradiated by neutrons and electrons and Damage behaviors of NdFeB permanent magnets irradiated by electrons and protons were studied systematically. Microstructures of these materials were studied by XRD, TEM. Defects induced by irradiation were studied by Positron Annihilation Life Spectroscope (PALS). Hyperfine structures of Segment neodymium magnets these alloys were studied by M?ssbauer spectroscope.Results of electrons irradiation experiments indicate that, magnetic flux of all 3 kinds of NdFeB alloys decreases obviously after electron irradiation, and the magnetic flux decreased with the increase of dose of electorn irradiation.
　　The decrease of magnetic flux of alloy N35 is the most remarkable, alloy N53 is the next, and N35EH is the most inapparent. NdFeB magnets with high coercivity and high magnetic energy products have strong irradiation resistance. Magenetic flux of FeCrCo nearly does not attenuation after electron irradiation. The investigation results of XRD and PALS show that the crystal structure and defects do not change after electorn irradiation. Magnetic flux of FeCrCo alloy and NdFeB alloy irradiated by electrons shows reversible changes.The decrease of magnetic flux of N35EH and N53 alloy are especially remarkable after proton irradiation. Results of XRD and PALS http://www.999magnet.com experiments indicate that the crystal structure and vacancy defects do not change. Magnetic flux revert completely after charge magnetism. Proton irradiation don’t induce the change in structure of the materials. The nucleation and growth of reversal domain induced by irradiation is thought to be the main reason that causes the demagnetization of NdFeB magnets.The loss of magnetic flux of FeCrCo alloy after neutron is remarkable. The changes in coercivity are small, but the residual magnetization and the magnetic induction shows obvious irreversible loss. The results of TEM and XRD analysis indicate that irradiation lead to diffusion of alloy elements, although the crystal structure does not change. PALS studies show that vacancy cluster increases by neutron irradiation. M?ssbauer spectroscopy analysis indicates that the part of paramagnetic phase decreases while ferromagnetic phase increses, and hyperfine magnetic field shifts to higher field after irradiation.