Nd_7Fe_(61)B_(22)Mo_4Y_6纳米复合永磁材料的磁性能及微结构
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摘要
采用铜模喷注法成功制备了尺寸为1×5×50 mm的长片状Nd_7Fe_(61)B_(22)Mo_4Y_6合金。通过差式扫描量热分析、X射线衍射分析及磁性能测量系统研究了合金的热稳定性、相组成及磁性能。结果表明,合金的磁性能对于热处理条件极为敏感,铸态合金显示软磁性能,经不同温度热处理后,其磁性转变为硬磁特性。通过740℃等温退火10 min,合金表现出最佳磁学性能,其中剩磁0.51 T,矫顽力1289 kA/m,最大磁能积46.2 kJ/m3。Nd_7Fe_(61)B_(22)Mo_4Y_6合金优良的磁性能可以归结为软磁相颗粒α-Fe、Fe3B和硬磁相颗粒Nd2Fe14B之间强烈的交换耦合作用。由于其尺寸大和磁性能良好的特点,Nd-Fe-B-Mo-Y系纳米复合永磁合金具有潜在的应用价值。
The Nd_7Fe_(61)B_(22)Mo_4Y_6 sheet alloys with dimension of 1×5×50 mm have been prepared by copper mold casting technique. The thermal behavior, microstructure and magnetic properties of the magnets have been investigated by differential scanning calorimetry, X-ray diffractometry and magnetometry techniques. The as-cast Nd_7Fe_(61)B_(22)Mo_4Y_6 alloy exhibits soft magnetic properties, which changes into magnetically hard after annealing. Results show that the magnetic properties of the alloy are sensitive to thermal processing conditions. The optimum hard magnetic properties with remanence(Br) of 0.51 T,coercivity(Hci) of 1289 kA/m and maximum energy product(BH)max of 46.2 kJ/m3 were achieved after annealing the alloy at740 ℃ for 10 min. The good magnetic properties of the Nd_7Fe_(61)B_(22)Mo_4Y_6 magnets are ascribed to the exchange coupling between the nano-scaled soft α-Fe, Fe3 B and hard Nd2 Fe14 B magnetic grains. Large size bulk nanocomposite magnets with sound magnetic properties make the Nd-Fe-B-Mo-Y alloy system a promising candidate for industrial applications.
The Nd_7Fe_(61)B_(22)Mo_4Y_6 sheet alloys with dimension of 1×5×50 mm have been prepared by copper mold casting technique. The thermal behavior, microstructure and magnetic properties of the magnets have been investigated by differential scanning calorimetry, X-ray diffractometry and magnetometry techniques. The as-cast Nd_7Fe_(61)B_(22)Mo_4Y_6 alloy exhibits soft magnetic properties, which changes into magnetically hard after annealing. Results show that the magnetic properties of the alloy are sensitive to thermal processing conditions. The optimum hard magnetic properties with remanence(Br) of 0.51 T,coercivity(Hci) of 1289 kA/m and maximum energy product(BH)max of 46.2 kJ/m3 were achieved after annealing the alloy at740 ℃ for 10 min. The good magnetic properties of the Nd_7Fe_(61)B_(22)Mo_4Y_6 magnets are ascribed to the exchange coupling between the nano-scaled soft α-Fe, Fe3 B and hard Nd2 Fe14 B magnetic grains. Large size bulk nanocomposite magnets with sound magnetic properties make the Nd-Fe-B-Mo-Y alloy system a promising candidate for industrial applications.
引文
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[2]Coehoorn R,De Mooij D B,Duchateau J P W B,et al.Novel permanent magnetic materials made by rapid quenching[J].Journal de Physique,1988,C8(49):669-670.
[3]Chang H W,Shih M F,Hsieh C C,et al.Magnetic property enhancement of directly quenched Nd-Fe-B bulk magnets with Ti substitution[J].J Alloys Compds,2010,489(2):499-503.
[4]Sheng H C,Zeng X R,Qian H X,et al.Effect of melt treatment on the microstructure and magnetic properties of Nd2Fe14B/α-Fe nanocomposites[J].J Non-Cryst Solids,2010,356(1):19-23.
[5]龙卧云,卢安贤.块体非晶合金的应用研究进展[J].材料导报,2009,23(19):61-66.
[6]Pawlik P,Davies H A.Glass formability of Fe-Co-Pr-Dy-Zr-B alloys and magnetic properties following devitrification[J].J Scr Mater,2003,49(8):755-760.
[7]Tan X H,Xu H,Bai Q,et al.Magnetic properties of Fe-Co-Nd-Y-B magnet prepared by suction casting[J].JNon-Cryst Solids,2007,353(4):410-412.
[8]Zhang W Y,Stoica M,Eckert J,et al.Preparation of bulk Nd2Fe14B/Fe3B nanocomposite magnets with high rare earth content[J].J Intermetallics,2008,16(3):341-344.
[9]Jian H,Luo W,Tao S,et al.Mechanical and magnetic properties of(Fe72Mo4B24)100-xTbx(x=4,5,6,7 at.%)bulk glassy alloys[J].J Alloys Compds,2010,505(1):315-318.
[10]Tao S,Ahmad Z,Jian H,et al.Synthesis,thermal stability and properties of[(Fe1-xCox)72Mo4B24]94Dy6 bulk metallic glasses[J].J Alloys Compds,2011,509(9):3843-3846.
[11]Chang H W,Shih M F,Chang C W,et al.Magnetic properties,phase evolution and microstructure of directly quenched bulk Pr-Fe-B-Nb magnets[J].J Scr Mater,2008,59(2):227-230.
[12]Chang H W,Shih M F,Chang C W,et al.Magnetic properties and microstructure of directly quenched Nd9.5Fe75.5-xMx B15(M=Mo,Nb,Ta,Ti,V,and Zr;x=0.4)bulk magnets[J].J Appl Phys,2008,103(7):07E1051-07E1053.
[13]Chang H W,Gan J Y,Hsieh C C,et al.Effects of C and Cr contents on the magnetic properties and microstructure of directly quenched NdFeTiZrCrBC bulk magnets[J].J Appl Phys,2010,107(7):09A7401-09A7403.
[14]Chang H W,Cheng Y T,Chang C W,et al.Improvement of size and magnetic properties of Nd9.5Fe75.5Ti3B15 Bulk magnets by Zr or Nb substitution for Ti[J].J Appl Phys,2009,105(7):07A7421-07A7423.
[15]Chang H W,Hsieh C C,Gan J Y,et al.Alloying effect on the magnetic properties of RFeB-type bulk magnets[J].JAppl Phys,2011,44(6):0640021-06400210.
[16]Tao S,Ma T Y,Ahmad Z,et al.Nd5Fe64B23Mo4Y4 bulk nanocomposite permanent magnets produced by crystallizing amorphous precursors[J].J Non-Cryst Solids,2012,358(6-7):1028-1031.
[17]Wu Q,Yan A R,Ge H L,et al.Synthesis,structure,and magnetic properties of Nd-Y-Fe-Mo-B bulk nanocomposite magnets[J].J Appl Phys,2011,109(7):07A7391-07A7393.
[18]Tan X H,Xu H,Bai Q,et al.Fe-Zr-Nd-Y-B permanent magnet derived from crystallization of bulk amorphous alloy[J].J Appl Phys Lett,2007,91(25):252501-252503.
[19]Wohlfarth E P.Relations between different modes of acquisition of remanent magnetization of ferromagnetic particles[J].J Appl Phys,1958,29(3):595-596.