16:15 〜 16:35
[14E-T16-04] Study on Microstructure and Magnetic Properties of Grain Boundary Diffusion Processed Nd-Fe-B Sintered Magnet
キーワード：Heavy Rare-earth Elements, Nd-Fe-B magnet, Grain boundary diffusion process, EPMA
Nd-Fe-B sintered magnets are widely used in mechanical devices such as motors and generators that require high torque. Recently, there have been difficulties in using Nd-Fe-B permanent magnets in electric vehicle due to the high operating temperature of the drive motors, which exceeds 150 ℃. To overcome this issue, heavy rare-earth elements (HRE) are added to enhance the coercivity, but they are extremely expensive and have limited resources, which has led to research efforts to reduce the use of HRE. The grain boundary diffusion process (GBDP) can enhance the coercivity by diffusing HRE into grain boundary of the Nd-Fe-B forming a core-shell structure in addition to reducing the use of HRE. In this study, we investigate microstructure and magnetic properties after the GBDP at the different heating rates. Diffusion depth, formation of a core-shell structure, composition depending on the GBDP conditions are analyzed and correlation between magnetic properties is discussed.