【作者】 张颖；

【导师】 崔春翔；

【作者基本信息】 河北工业大学 ， 材料学， 2005， 硕士

【摘要】 Sm₃（Fe,Ti）₂₉N_x/α-Fe双相纳米耦合永磁材料是由软磁相α-Fe提供较高的磁饱和强度,硬磁相Sm₃（Fe,Ti）₂₉N_x提供较高的矫顽力,两者在纳米尺度发生耦合作用,从而提高综合永磁性能,同时软磁相α-Fe的存在大大降低了稀土的含量,降低了成本,是目前最具应用潜力的研究方向。本文采用熔体快淬法结合晶化与氮化处理,通过添加稳定性合金元素Ti,成功制备了Sm₃（Fe,Ti）₂₉N_x和α-Fe纳米双相耦合永磁材料,并对其制备过程中的晶化工艺、氮化工艺、微结构和磁性能进行了详细地分析和研究。Sm₁₀Fe₈₄Ti₆合金和Sm₁₀Fe₈₄Ti₅Cu₁合金的铸态和退火态组织均由四种物相构成,α-Fe相、Sm₃（Fe,Ti）₂₉相、少量Sm₂（Fe,Ti）₁₇相及富钐相SmFe₂,但Sm₁₀Fe₈₄Ti₆合金和Sm₁₀Fe₈₄Ti₅Cu₁合金退火后的α-Fe和富钐相相对铸态合金含量减少,Sm₃（Fe,Ti）₂₉相和Sm₂（Fe,Ti）₁₇相的相对含量增多。甩带后样品中只有Sm₃（Fe,Ti）₂₉和α-Fe两种物相,且Sm₃（Fe,Ti）₂₉相存在部分非晶。Sm₁₀Fe₈₄Ti₆及退火态Sm₁₀Fe₈₄Ti₆薄片700℃晶化后,细小晶粒间有类似非晶形态的物质,750℃保温30min的晶化条件使薄片完全晶化,用透射电子显微镜观察到晶粒与晶粒之间紧密结合,晶粒尺寸一般在50nm以下,晶界平直光滑,能达到晶粒间较好的直接交换耦合。而添加Cu的合金薄带晶粒分布较混乱,晶粒大小差别较大,在晶界位置有细小晶粒析出,晶粒间结合没有规律,晶界也不是典型的平直光滑。四种合金氮化后均由Sm₃（Fe,Ti）₂₉N_x和α-Fe两相构成。四种合金矫顽力和剩磁均在750℃晶化时达到最大值,但未添加Cu的合金磁性能要远高于添加Cu的合金磁性能,Sm₁₀Fe₈₄Ti₆合金在15000Oe外场下的矫顽力最高值为750℃晶化时的1778.4Oe。未添加Cu的合金磁滞回线比较光滑丰满,说明3:29相与α-Fe存在很好的纳米交换耦合。更多还原

【Abstract】 Sm3(Fe,Ti)29Nx/a-Fe dual-coupling nanocomposite permanent magnets have excellent magnetic properties due to the dual-coupling effects between the soft magnetic phase a-Fe which provides high saturation magnetization and the hard magnetic phase Sm3(Fe,Ti)29Nx which offers high coercivity, moreover the existence of soft magnetic phase a-Fe largely decreases the content of rare earth and the cost. So the study has the most potential for the application of magnets. In this paper, Sm3(Fe,Ti)29Nx and a-Fe dual-coupling nanocomposite magnets have been successfully fabricated with the addition of stable element Ti and with the help of the melt-spun, crystallization and nitrogenation techniques. And the techniques of crystallization and nitrogenation, the microstructure and the magnetic properties have also been studied in detail. For Sm10Fe84Ti6 and Sm10Fe84Ti5Cu1, both the cast and annealed alloys are composed of four kinds of phases such as a-Fe, Sm3(Fe,Ti)29, little amount of Sm2(Fe,Ti)17 and SmFe2, but the contents of a-Fe and SmFe2 decrease and the contents of Sm3(Fe,Ti)29 and Sm2(Fe,Ti)17 increase after annealing compared with the cast alloys. Only Sm3(Fe,Ti)29 and a-Fe exist in the melt-spun alloys, and Sm3(Fe,Ti)29 phase is a little amorphous. For Sm10Fe84T16 and annealed Sm10Fe84Ti6 alloys, when crystallized at 700℃ some fine grains are separated hy amorphous phase, and when crystallized at 750 ℃ for30min the ribbon is totally crystallized from which the tight binding between grains and straight smooth interface with fine grains less than 50nm can be observed by TEM. However different grains are disorderly distributed in the ribbons of Cu-added alloys with fine grains precipitated along the coarse interface. Only Sm3(Fe,Ti)29Nx and a-Fe exist in the four kinds of nitrogenated alloys. And all of the coercivity and remnant magnetism reach the maximum when crystallization at 750℃. The magnetic properties of the alloy without the addition of Cu are better than those of the alloy with the addition of Cu. The maximum coercivity of Sm10Fe84Ti6 is 1778.4 Oe when measured in the field of 15000Oe. The hysteresis loop is smooth and full for the alloy without the addition of Cu which means good dual-coupling exists between Sm3(Fe,Ti)29Nx and a-Fe nano-grains.更多还原