부산대학교 도서관

It has been suggested in a previous publication that the magnetization of Sm2Fe17N3 anisotropic sintered magnets prepared from jet-milled powder is unexpectedly low. This study was conducted to clarify the cause of the reduction in magnetization from a metallographic point of view. Sm2Fe17N3 powders prepared by jet milling in a low-oxygen atmosphere were aligned in a magnetic field and then sintered by pressure current sintering (PCS) method. The smaller the grain size, the worse the crystallinity because of the milling damages on the raw powders. Magnetization of the sintered bodies decreased as the crystallinity got worse, which is qualitatively similar to the trend for the powders, but the absolute values converged to a fairly lower level. Based on the results of microstructural analysis, it is inferred that the damaged regions with high density dislocations are converted into isotropic nanocrystals under the influence of heat and pressure upon sintering, resulting in a certain loss of crystal alignment, which is considered to be the principal cause of the reduction in magnetization.