Sensitivity of coercivity and squareness factor of a Nd-Fe-B sintered magnet on post-sintering annealing temperature  

作　　者：梁乐 武梦艳 刘丽华 马冲 王静 张江东 张澜庭 

机构地区：[1]School of Materials Science and Engineering, Shanghai Jiao Tong University [2]Shanghai Roco Magnetics Co., Ltd.

出　　处：《Journal of Rare Earths》2015年第5期507-513,共7页稀土学报（英文版）

基　　金：Project supported by the National Natural Science Foundation of China(51171111)

摘　　要：An N38SH-grade magnet with low oxygen content was used to study the evolution of magnetic properties upon post-sin-tering annealing. Phase transformation of as-sintered magnet was investigated by differential scanning calorimetry （DSC）. Three low temperature eutectic transition points were detected. Little change could be found when annealed below the lowest eutectic transition point. A wide annealing temperature range （460–560 oC） between the lowest and highest eutectic transition point was available for this magnet to achieve a relatively high coercivity （~1671 kA/m） at a relatively low Dy content （~3 wt.%）. However, squareness fac-tor （SF） of the demagnetizing curve and its temperature stability were found to decrease after annealing above the highest eutectic transition point. This was attributed to the change of Cu content in the Nd-rich phase under different annealing temperatures.An N38SH-grade magnet with low oxygen content was used to study the evolution of magnetic properties upon post-sin-tering annealing. Phase transformation of as-sintered magnet was investigated by differential scanning calorimetry （DSC）. Three low temperature eutectic transition points were detected. Little change could be found when annealed below the lowest eutectic transition point. A wide annealing temperature range （460–560 oC） between the lowest and highest eutectic transition point was available for this magnet to achieve a relatively high coercivity （~1671 kA/m） at a relatively low Dy content （~3 wt.%）. However, squareness fac-tor （SF） of the demagnetizing curve and its temperature stability were found to decrease after annealing above the highest eutectic transition point. This was attributed to the change of Cu content in the Nd-rich phase under different annealing temperatures.

关 键 词：Nd-Fe-B sintered magnet DSC COERCIVITY squareness factor annealing rare earths 

分 类 号：TM273[一般工业技术—材料科学与工程] TB383[电气工程—电工理论与新技术]