HDDR处理的不同钐含量Sm_2Fe_(17)型合金及氮化物的研究

Effect of the Excess Sm on the Sm_2Fe_(17)-Type Alloys and Their Nitrides by HDDR Processes

通过采用电弧炉冶炼、HDDR及氮化的方法,对Sm2Fe17型合金及其氮化物的组织形貌、物相及磁性能进行研究发现,多补偿添加25%钐可使Sm2Fe17型合金退火后的α-Fe含量小于2%。HDDR后的粉末颗粒表面由蜂窝状孔洞、密堆积小颗粒及弥散细小颗粒组成。不同次数HDDR循环处理后的主相均表现为与退火后相同的Sm2Fe17结构及易面磁化。HDDR后α-Fe的含量增加,单胞体积膨胀?V/V<0.35%。氮化后Sm2Fe17晶格膨胀形成Sm2Fe17Nx主相,α-Fe相膨胀小,氮化增加α-Fe含量,多补偿Sm和延长氮化时间对减少α-Fe含量有利。随着氮化时间的延长,粉末中的氮含量增加,而且细粉氮化速度快,其中Sm12.8Fe87.2细粉氮化速度最快。补偿足够的钐可提高磁性能,从提高矫顽力角度看,多添加25%Sm与40%Sm效果相当,但从提高剩磁角度看,多添加钐到40%更好。

The micro structures, phase compositions, magnetic properties of Sm2F17-type alloys and their nitrides have been studied by means of arc-melting, HDDR and nitrogenation processes. it was found that excess 25% Sm in Sm2Fe17 could decrease the content of alpha-Fe in annealed Sm2Fe17-type alloys to less than 2%. The rough particle surfaces by HDDR processes were composed of cell, close-packed particles and scattered fine particles. The characteristics Of Sm2Fe17-type main phase structure and easy-plane magnetization by two or four cycles of HDDR processes were the same with that of annealed alloys, however, the HDDR processes promoted the content of a-Fe. Nitrogenation process converted the main phase from Sm2Fe17 to Sm2Fe17Nx followed by lattice expansion, however. The nitrogen content among three types of alloys increased with increasing of nitrogenation time, the nitrogen content in fine powders with the size below 40 mu m was evidently higher than that of coarse powder with the size between 175 mu m and 246 mu m and the Sm12.8Fe87.2Nx fine powders presented the highest nitrogen content. Nitrogenation process increased the content of a-Fe, on the contrary, the excess Sm and extending nitrogenation time were benefit for decreasing of the content of a-Fe. The proper excess Sm contributes to improve the magnetic properties of Sm12Fe17-type nitrides, and as far as coercivity is concerned; the roles of excess 25% Sm for Sm12.8Fe87.2Nx with the maximum coercivity of 1216 Oe or 40%Sm for Sm14.2Fe85.8Nx with the peak coercivity of 1096 Oe were almost equivalent, but concerning the remanence, the excess 40% Sm was much better.