Fe对SmCo基高温永磁体微观结构及矫顽力的影响
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摘要
制备了在500℃下矫顽力为603.99 k A/m,最大磁能积为87.30 k J/m3的高温磁体。研究发现,在室温下,Fe含量较高的SmCo基磁体矫顽力较大,而高温下Fe含量高的磁体矫顽力较小。对磁体的微观形貌、相组成及磁体胞壁胞内成分进行分析,结果表明,随Fe含量升高,胞尺寸变大,1:5H相含量减少,胞壁相中Cu含量及胞内相中Fe含量升高。Fe和Cu元素在胞壁和胞内两相中含量的改变,导致了室温及高温两相畴壁能差的改变,从而引起了矫顽力的变化。
High-temperature permanent magnets have an important application in the aerospace and other high-tech fields, among which 2:17-type SmCo magnets have become the first choice for hightemperature permanent magnets due to the strong magnetic anisotropy and high Curie temperature. Although there are studies on the effect of Fe on the remanence and coercivity, the role that Fe plays on coercivity mechanism of SmCo magnets is still unclear. In this work, Sm(CobalFexCu0.08~0.10Zr0.03~0.033)z(x=0.10~0.16, z=6.90 and 7.40) magnets are prepared and the magnetic properties under different temperatures are investigated. The magnets with an intrinsic coercivity of 603.99 k A/m and a maximum energy product of 87.30 k J/m3 at 500 ℃ are obtained. It is revealed that at room temperature the coercivity of the magnets increases with increasing Fe content, however, at 500 ℃ the coercivity shows an opposite dependency on Fe content. Moreover, the effect of Fe on coercivity is more obvious at low z value. The phase structure and composition analyses were characterized by XRD and TEM. The results show that with the increase of Fe content, the size of the 2:17R cell phase increases, the volume ratio of cell boundary 1:5H phase decreases, and furthermore, both Fe content in the 2:17R phase and Cu content in the 1:5H phase increase. The variations of Fe and Cu contents in both phases lead to the change of the domain wall energy difference. With the increase of Cu content of 1:5H phase, the domain wall energy of 1:5H phase(g1:5) drops faster at room temperature, the coercivity is determined by g2:17-g1:5, so the coercivity increases with increasing Fe content. While at 500 ℃, due to g1:5at its Curie temperature, the coercivity is mainly determined by the domain wall energy of 2:17R phase(g2:17), which decreases with increasing Fe content. The increase of Fe content at the low z value results in a smaller growth of cell size, which leads to a more significant change in coercivity.
High-temperature permanent magnets have an important application in the aerospace and other high-tech fields, among which 2:17-type SmCo magnets have become the first choice for hightemperature permanent magnets due to the strong magnetic anisotropy and high Curie temperature. Although there are studies on the effect of Fe on the remanence and coercivity, the role that Fe plays on coercivity mechanism of SmCo magnets is still unclear. In this work, Sm(CobalFexCu0.08~0.10Zr0.03~0.033)z(x=0.10~0.16, z=6.90 and 7.40) magnets are prepared and the magnetic properties under different temperatures are investigated. The magnets with an intrinsic coercivity of 603.99 k A/m and a maximum energy product of 87.30 k J/m3 at 500 ℃ are obtained. It is revealed that at room temperature the coercivity of the magnets increases with increasing Fe content, however, at 500 ℃ the coercivity shows an opposite dependency on Fe content. Moreover, the effect of Fe on coercivity is more obvious at low z value. The phase structure and composition analyses were characterized by XRD and TEM. The results show that with the increase of Fe content, the size of the 2:17R cell phase increases, the volume ratio of cell boundary 1:5H phase decreases, and furthermore, both Fe content in the 2:17R phase and Cu content in the 1:5H phase increase. The variations of Fe and Cu contents in both phases lead to the change of the domain wall energy difference. With the increase of Cu content of 1:5H phase, the domain wall energy of 1:5H phase(g1:5) drops faster at room temperature, the coercivity is determined by g2:17-g1:5, so the coercivity increases with increasing Fe content. While at 500 ℃, due to g1:5at its Curie temperature, the coercivity is mainly determined by the domain wall energy of 2:17R phase(g2:17), which decreases with increasing Fe content. The increase of Fe content at the low z value results in a smaller growth of cell size, which leads to a more significant change in coercivity.
引文
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[17]Tang W,Zhang Y,Gabay A M,et al.Anomalous temperature dependence of coercivity in rare earth cobalt magnets[J].J.Magn.Magn.Mater.,2002,242-245:1335
[18]Tang W,Zhang Y,Hadjipanayis G C,et al.Influence of Zr and Cu content on the microstructure and coercivityin Sm(CobalFe0.1CuyZrx)8.5magnets[J].J.Appl.Phys.,2000,87:5308
[19]Chen C H,Walmer M S,Walmer M H.Sm2(Co,Fe,Cu,Zr)17magnets for use at temperature?400℃[J].J.Appl.Phys.,1998,83:6706
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[21]Liu J F,Ding Y,Hadjipanayis G C.Effect of iron on the high temperature magnetic properties and microstructure of Sm(Co,Fe Cu,Zr)zpermanent magnets[J].J.Appl.Phys.,1999,85:1670
[22]Wang F Z.Modern Methods for Material Analysis[M].Beijing Beijing Institute of Technology Press,2006:74(王富耻.材料现代分析测试方法[M].北京:北京理工大学出版社,2006:74)
[23]Sun T D.A model on the coercivity of the hardened 2-17 rar earth-cobalt permanent magnets[J].J.Appl.Phys.,1981,52:2532
[24]Lectard E,Allibert C H,Ballou R.Saturation magnetization and anisotropy fields in the Sm(Co1-xCux)5phases[J].J.Appl.Phys.1994,75:6277
[25]Miyazaki T,Takahashi M,Yang X B,et al.Formation of meta stable compounds and magnetic properties in rapidly quenched(Fe1-xCox)5Sm and(Fe1-xCox)7Sm2alloy systems[J].J.Appl.Phys.1988,64:5974
[26]Goll D,Kronmüller H,Stadelmaier H H.Micromagnetism and th microstructure of high-temperature permanent magnets[J].J.Ap pl.Phys.,2004,96:6534
[2]Gutfleisch O,Willard M A,Brück E,et al.Magnetic materials and devices for the 21st century:Stronger,lighter,and more energy effi cient[J].Adv.Mater.,2011,23:821
[3]Horiuchi Y,Hagiwara M,Okamoto K,et al.Effects of solution treat ed temperature on the structural and magnetic properties of iron rich Sm(Co Fe Cu Zr)zsintered magnet[J].IEEE Trans.Magn.,201349:3221
[4]Zhang T L,Liu H Y,Liu J H,et al.2:17-type Sm Co quasi single-crystal high temperature magnets[J].Appl.Phys.Lett.,2015106:162403
[5]Wang Q,Jiang C B.Study on Sm Co permanent magnets unde350℃moderate temperatures[J].Acta Metall.Sin.,2011,47:1605(王倩,蒋成保.350℃中温段Sm Co永磁材料的研究[J].金属学报,2011,47:1605)
[6]Guo Z H,Li W.Room-and high-temperature magnetic properties of Sm(CobalFexCu0.088Zr0.025)7.5(x=0~0.30)sintered magnets[J].Acta Metall.Sin.,2002,38:866(郭朝晖,李卫.Sm(CobalFexCu0.088Zr0.025)7.5(x=0~0.30)烧结永磁体的磁性及其高温特性[J].金属学报,2002,38:866)
[7]Liu J F,Ding Y,Zhang Y,et al.New rare-earth permanent magnets with an intrinsic coercivity of 10 k Oe at 500℃[J].J.Appl.Phys.,1999,85:5660
[8]Panagiotopoulos I,Matthias T,Niarchos D,et al.Melt-spun Sm(Co,Fe,Cu,Zr)zmagnets for high-temperature applications[J].J.Magn.Magn.Mater.,2002,242-245:1304
[9]Zhang T L,Liu H Y,Ma Z H,et al.Single crystal growth and magnetic properties of 2:17-type Sm Co magnets[J].J.Alloys Compd.,2015,637:253
[10]Wang G J,Zheng L,Jiang C B.Magnetic domain structure and temperature dependence of coercivity in Sm(CobalFe0.1Cu0.1Zr0.033)z(z=6.8,7.4)magnets[J].J.Magn.Magn.Mater.,2013,343:173
[11]Li L Y,Yi J H,Huang B Y,et al.Microstructure and magnetic properties of Sm2Co17-based high temperature permanent magnets[J].Acta Metall.Sin.,2005,41:791(李丽娅,易健宏,黄伯云等.Sm2Co17基高温稀土永磁材料的显微结构与磁性[J].金属学报,2005,41:791)
[12]Kronmüller H,Goll D.Micromagnetic analysis of pinninghardened nanostructured,nanocrystalline Sm2Co17based alloys[J].Scr.Mater.,2002,47:545
[13]Xiong X Y,Ohkubo T,Koyama T,et al.The microstructure of sintered Sm(Co0.72Fe0.20Cu0.055Zr0.025)7.5permanent magnet studied by atom probe[J].Acta Mater.,2004,52:737
[14]Liu J F,Zhang Y,Hadjipanayis G C.High-temperature magnetic properties and microstructural analysis of Sm(Co,Fe,Cu,Zr)zpermanent magnets[J].J.Magn.Magn.Mater.,1999,202:69
[15]Wang G J,Jiang C B.The coercivity and domain structure of Sm(CobalFe0.1CuxZr0.033)6.9(x=0.07,0.10,0.13)high temperature permanent magnets[J].J.Appl.Phys.,2012,112:033909
[16]Liu J F,Chui T,Dimitrov D,et al.Abnormal temperature dependence of intrinsic coercivity in Sm(Co,Fe,Cu,Zr)zpowder materials[J].Appl.Phys.Lett.,1998,73:3007
[17]Tang W,Zhang Y,Gabay A M,et al.Anomalous temperature dependence of coercivity in rare earth cobalt magnets[J].J.Magn.Magn.Mater.,2002,242-245:1335
[18]Tang W,Zhang Y,Hadjipanayis G C,et al.Influence of Zr and Cu content on the microstructure and coercivityin Sm(CobalFe0.1CuyZrx)8.5magnets[J].J.Appl.Phys.,2000,87:5308
[19]Chen C H,Walmer M S,Walmer M H.Sm2(Co,Fe,Cu,Zr)17magnets for use at temperature?400℃[J].J.Appl.Phys.,1998,83:6706
[20]Guo Z H,Pan W,Li W.Sm(Co,Fe,Cu,Zr)zsintered magnets with a maximum operating temperature of 500℃[J].J.Magn.Magn.Mater.,2006,303:e396
[21]Liu J F,Ding Y,Hadjipanayis G C.Effect of iron on the high temperature magnetic properties and microstructure of Sm(Co,Fe Cu,Zr)zpermanent magnets[J].J.Appl.Phys.,1999,85:1670
[22]Wang F Z.Modern Methods for Material Analysis[M].Beijing Beijing Institute of Technology Press,2006:74(王富耻.材料现代分析测试方法[M].北京:北京理工大学出版社,2006:74)
[23]Sun T D.A model on the coercivity of the hardened 2-17 rar earth-cobalt permanent magnets[J].J.Appl.Phys.,1981,52:2532
[24]Lectard E,Allibert C H,Ballou R.Saturation magnetization and anisotropy fields in the Sm(Co1-xCux)5phases[J].J.Appl.Phys.1994,75:6277
[25]Miyazaki T,Takahashi M,Yang X B,et al.Formation of meta stable compounds and magnetic properties in rapidly quenched(Fe1-xCox)5Sm and(Fe1-xCox)7Sm2alloy systems[J].J.Appl.Phys.1988,64:5974
[26]Goll D,Kronmüller H,Stadelmaier H H.Micromagnetism and th microstructure of high-temperature permanent magnets[J].J.Ap pl.Phys.,2004,96:6534