材料期刊网

制备了在500℃下矫顽力为603.99 kA/m,最大磁能积为87.30 kJ/m3的高温磁体.研究发现,在室温下,Fe含量较高的SmCo基磁体矫顽力较大,而高温下Fe含量高的磁体矫顽力较小.对磁体的微观形貌、相组成及磁体胞壁胞内成分进行分析,结果表明,随Fe含量升高,胞尺寸变大,1∶5H相含量减少,胞壁相中Cu含量及胞内相中Fe含量升高.Fe和Cu元素在胞壁和胞内两相中含量的改变,导致了室温及高温两相畴壁能差的改变,从而引起了矫顽力的变化.

High-temperature permanent magnets have an important application in the aerospace and other high-tech fields,among which 2∶17-type SmCo magnets have become the first choice for high-temperature permanent magnets due to the strong magnetic anisotropy and high Curie temperature.Although there are studies on the effect of Fe on the remanence and coercivity,the role that Fe plays on coercivity mechanism of SmCo magnets is still unclear.In this work,Sm(CobalFexCu0.08-0.10Zr0.03-0.033)z (x=0.10～0.16,z=6.90 and 7.40) magnets are prepared and the magnetic properties under different temperatures are investigated.The magnets with an intrinsic coercivity of 603.99 kA/m and a maximum energy product of 87.30 kJ/m3 at 500 ℃ are obtained.It is revealed that at room temperature the coercivity of the magnets increases with increasing Fe content,however,at 500 ℃ the coercivity shows an opposite dependency on Fe content.Moreover,the effect of Fe on coercivity is more obvious at low z value.The phase structure and composition analyses were characterized by XRD and TEM.The results show that with the increase of Fe content,the size of the 2∶17R cell phase increases,the volume ratio of cell boundary 1∶5H phase decreases,and furthermore,both Fe content in the 2∶17R phase and Cu content in the 1∶5H phase increase.The variations of Fe and Cu contents in both phases lead to the change of the domain wall energy difference.With the increase of Cu content of 1∶5H phase,the domain wall energy of 1∶5H phase (γ1∶5) drops faster at room temperature,the coercivity is determined by γ2∶17-γ1∶5,so the coercivity increases with increasing Fe content.While at 500 ℃,due to γ1∶5 at its Curie temperature,the coercivity is mainly determined by the domain wall energy of 2∶17R phase (γ2∶17),which decreases with increasing Fe content.The increase of Fe content at the low z value results in a smaller growth of cell size,which leads to a more significant change in coercivity.