Magnetic Properties of Nd-Fe-B-M (M=Si, C) Bulk Nanocomposite Magnets Prepared by the Spark Plasma Sintering Method

摘要

We have prepared Nd_2Fe_(14)B/Fe_3B bulk nanocomposite magnets at the compositions Nd_4Fe_(77.5)B_(18.5-x)M_x(M=Si, C) by substituting other elements M for B. For the sample substituted with 1 at.%Si, the coercivity exhibits the highest value of 227 kA/m when sintered at 600 °C. In addition, the grain sizes of the Nd_2Fe_(14)B and the Fe_3B phases are found to depend on the ramp-up time during sintering and the reduction of the grain size leads to an increase of the coercivity. On the other hand, the samples substituted with C exhibit soft magnetic behaviors, which is attributed to the suppression of the Nd_2Fe_(14)B hard phase.