HDDR处理的Sm_2Fe_(16.5)Ti_(0.5)合金的结构与氮化(英文)

Structural and nitrogenation of Sm_2Fe_(16.5)Ti_(0.5) alloy prepared by HDDR process

采用HDDR及氮化工艺制备了Sm2Fe16.5Ti0.5Ny粉末。铸态Sm2Fe16.5Ti0.5合金存在择优取向,Sm2(Fe,Ti)17主相的214衍射峰增强。均匀化退火后,只有约0.6%的-αFe(Ti)相与主相Sm2(Fe,Ti)17共存。经不同循环的HDDR工艺处理后,物相组成不发生变化,但-αFe(Ti)相含量增加。HDDR工艺有助于获得细晶结构,提高磁粉的矫顽力。HDDR处理的合金的氮化由初期的Sm-Fe-Ti合金与氮快速反应阶段及后期氮在合金中的均匀化扩散阶段组成。随着氮化时间的延长,富铁相含量增加。氮化物中Sm2(Fe,Ti)17Ny主相的晶格膨胀行为由HDDR与氮化工艺共同决定。在500℃氮化2h后,796kA/m最大外场下得到的最大矫顽力为164.9kA/m,氮化12h时后得到最大剩磁45.7Am2/kg。

Sm2Fe16.5Ti0.5Ny powder is synthesized by HDDR process and nitrogenation. As-cast Sm2 Fe16.5Ti0.5 alloy behaves preferred direction, which is the 214 diffraction of Sm2 （Fe, Ti）17. In the as-homogenized ingots, main phase Sm2（Fe, Ti）17 co-exists with only about 0.6% a-Fe（Ti）. After treated by different cycles of HDDR process, the phase compositions aren＇t changed any more, but the content of α-Fe（Ti） is increased. Moreover, HDDR process contributes to the fine-grained mierostructure and improves the coercivity. The nitrogenation process mainly includes two stages, one is fast reaction between N and Sm-Fe-Ti phase, another is lengthy homogenized diffusion of N. The content of Fe-rieh phases is increased with increasing nitrogenation time. The lattice expansion of Sm2 （Fe,Ti）17Ny nitrides is controlled by HDDR and nitrogenation processes together. The optimal coercivity of 164.9kA/m is obtained at nitrogenation 2h, and the excellent remanence of 45.7Am^2/kg is presented at nitrogenation 12h.