添加不同钐含量的Sm_2Fe_(17)型合金及其氮化物的研究

Study on Sm_2Fe_(17)-type alloys and their nitrides with different Sm content

通过采用粉末冶金法及密封氮化的方法,对添加不同钐含量的Sm2Fe17型合金及其氮化物的组织形貌、物相组成与结构及磁性能进行了研究。结果发现,多补偿添加25%钐可以使Sm2Fe17型合金退火态的-αFe含量小于2%。Sm-Fe合金冶炼后的主相均表现为菱方Th2Zn17型结构,但快冷时优先沿{300}和{220}面长大。氮化后Sm2Fe17晶格膨胀形成Sm2Fe17Nx主相,而-αFe的X射线特征峰未见明显移动。Sm14.2Fe85.8合金晶胞膨胀相对较小,而Sm12.8Fe87.2晶胞膨胀较大,在氮化20h时有最大ΔV/V=8.36%。氮化增加合金中的-αFe含量。Sm14.2Fe85.8Nx的剩磁最高为59.5 Am2/kg,Sm10.5Fe89.5Nx磁化强度最高值为193.6 Am2/kg,Sm12.8Fe87.2Nx合金的所有磁性能值基本分布在Sm14.2Fe85.8Nx和Sm10.5Fe89.5Nx的值之间。

The microstructure, phase composition and magnetic properties of Sm2Fe17-type alloys and their nitrides with different Sm content were studied by means of powder metallurgy technique and air-tight nitrogenation. It is found that excess 25 % Sm could decrease the content of α-Fe in annealed alloy to less than 2%. The main phases of all as-cast Sm-Fe alloys behave the rhombohedral Th2Zn17-type structure. Moreover, quickly cooling process facilitates the {300} and {220} crystal planes of Sm2Fe17 phase to grow firstly. After the powder is nitrogenated, the main phase of Sm2Fe17Nx is formed with larger lattice expansion, however, the characteristic peaks of α-Fe phase don＇t show obvious shifting to lower angles. The lattice expansion of Sm2Fe17-type phase in Sm14.2Fe85.8Nx nitride is smaller, and that in Sm12.8Fe87.2Nx is larger, which has the maximum value of AV/V = 8.36% when nitrogenated for 20h. Nitrogenation process increases the content of α-Fe in nitrides. Sm14.2Fe85.8Nx shows the highest remanence of 59. 5 Am^2/kg. Sm10.5 Fe89.5 N, shows the highest magnetization of 193. 6 Am^2/kg. Furthermore, the magnetic properties of Sml2.8 Fe87.2 .Nx are between those of Sm14.2 Fe85.8 Nx and those of Sm10. 5 Fe89.5Nx.