-
钕铁硼磁体制备过程中出现的部分块体废料由于矫顽力较低,性能难以满足使用要求.本文主要通过晶界扩散技术来提高废料磁体的矫顽力.采用Pr70Cu30合金作为扩散介质,对烧结钕铁硼废料磁体进行了晶界扩散处理,研究了扩散温度、扩散时间和回火时间对扩散后的磁体性能的影响.结果显示,800℃下扩散3 h,磁体的矫顽力从原来的7.88 kOe(1 Oe=79.5775 A/m)提升至11.55 kOe,提升幅度为46.6%,同时剩磁没有明显降低.扩散后回火对矫顽力的提升有一定的作用.800℃下扩散4 h后的磁体在500℃回火3 h后,最高矫顽力可达11.97 kOe,比原磁体废料提高了51.9%,接近成品磁体的水平.显微组织分析证实了晶界扩散的作用.扩散处理后的磁体中,主相晶粒间形成了连续晶间相,起到有效的磁隔离作用,有利于矫顽力的提高.研究还发现,Pr70Cu30晶界扩散虽然可以使磁体腐蚀电位上升,但也会增加腐蚀电流密度,不利于磁体抗腐蚀性的改善.本文工作对于提高材料的成品率具有重要意义.Considerable quantities of Nd-Fe-B magnet wastes are produced every year worldwide. Some Nd-Fe-B magnet wastes in the bulk form, produced during manufacturing, have low coercivity and cannot meet the requirements for applications. Finding an effective way to reuse those wastes by improving the coercivity, without powdering or reproducing process, becomes very important for saving energy and raw materials in manufacture. In this work, the grain boundary diffusion process is carried out on waste Nd-Fe-B sintered magnets by using Pr70Cu30 as a diffusion medium. The effects of diffusion temperature, diffusion time, and annealing time on the magnetic properties of the magnets are investigated. It is found that the coercivity increases when the diffusion temperature increases from 500 to 800℃, the diffusion time increases from 1 to 3 h, or the annealing time increases from 1 to 3 h. By comparing the diffused sample with the simply heat treated sample, we find that the coercivity enhancement by grain boundary diffusion process indeed results from the infiltration of Pr and Cu elements. The coercivity of the magnet increases by 51.9%, from 7.88 kOe (1 Oe=79.5775 A/m) to 11.97 kOe, after 4-hour diffusion at 800℃ followed by 3-hour annealing, with a negligible reduction of remanence Br, achieving a 99.8% recovery of coercivity compared with the commercial N35 magnet. It is noted that 500℃ annealing for 3 h after 800℃ diffusion only slightly increases the coercivity by 4.6%, from 11.44 kOe to 11.97 kOe, which indicates that the annealing process after Pr-Cu grain boundary diffusion may be not indispensable. Based on the microstructure analysis, the diffusion of Pr and Cu is confirmed. However, the distributions of Pr and Cu are inhomogeneous within a range of tens of microns near the surface even though the diffusion has spread throughout the magnet. The structure of main phase grains separated by the continuous grain boundary phase is formed after the grain boundary diffusion process while the core-shell structure is not observed, which suggests that the modification of the grain boundary structure is the main reason for the coercivity improvement. Cu element plays an important role in forming continuous grain boundary phase. In addition, the electrochemical corrosion test shows that higher corrosion current is obtained in the diffused magnet than in the original magnet, though the corrosion potential is improved. The reduced corrosion resistance may be related to the increased RE-rich phase content and the formation of continuous grain boundary phase. The present work is of great importance for increasing the production yield of Nd-Fe-B magnets.
-
Keywords:
- Nd-Fe-B waste /
- grain boundary diffusion /
- coercivity /
- corrosion resistance
[1] Xu T 2004 Chin. Rare Earths 25 31 (in Chinese) [许涛 2004 稀土 25 31]
[2] Chen Y H, Wang H Y, Pei Y C, Ren J, Wang J J 2015 ACS Sustain. Chem. Eng. 3 3167
[3] Saito T, Sato H, Motegi T 2006 J. Alloys Compd. 425 145
[4] Sepehri-Amin H, Ohkubo T, Zakotnik M, Prosperi D, Afiuny P, Tudor C O, Hono K 2017 J. Alloys Compd. 694 175
[5] Li X T, Yue M, Liu W Q, Li X L, Yi X F, Huang X L, Zhang D T, Chen J W 2015 J. Alloys Compd. 649 656
[6] Zakotnik M, Tudor C O 2015 Waste Manage. 44 48
[7] Li C, Liu W Q, Yue M, Liu Y Q, Zhang D T, Zuo T Y 2014 IEEE Trans. Magn. 50 2105403
[8] Kawasaki T, Itoh M, Ken-Ichi M 2003 Mater. Trans. 44 1682
[9] Ma T Y, Wang X J, Liu X L, Wu C, Yan M 2015 J. Phys. D:Appl. Phys. 48 215001
[10] Oono N, Sagawa M, Kasada R, Matsui H, Kimura A 2011 J. Magn. Magn. Mater. 323 297
[11] Suzuki H, Satsu Y, Komuro M 2009 J. Appl. Phys. 105 07A734
[12] Guo S, Zhang X F, Ding G F, Chen R J, Lee D, Yan A R 2014 J. Appl. Phys. 115 17A754
[13] Watanabe N, Itakura M, Kuwano N, Li D, Suzuki S, Ken-Ich M 2007 Mater. Trans. 48 915
[14] Soderžnik M, Korent M, Soderžnik K Ž, Katter M, stner K, Kobe S 2016 Acta Mater. 115 278
[15] Tang M H, Bao X Q, Lu K C, Lu S, Li J H, Gao X X 2016 Scripta Mater. 117 60
[16] Liang L P, Ma T Y, Pei Z, Jin J Y, Mi Y 2014 J. Magn. Magn. Mater. 355 131
[17] Ji W X, Liu W Q, Yue M, Zhang D T, Zhang J X 2015 Physica B 476 147
[18] Chen F G, Zhang T Q, Jing W, Zhang L T, Zhou G F 2015 Scripta Mater. 107 38
[19] Akiya T, Liu J, Sepehri-Amin H, Ohkubo T, Hioki K, Hattori A, Hono K 2014 J. Appl. Phys. 115 17A766
[20] Tang X, Chen R, Yin W, Wang J Z, Lee D, Yan A R 2013 Appl. Phys. Lett. 102 72409
[21] Sepehri-Amin H, Liu J, Ohkubo T, Hioki K, Hattori A, Hono K 2013 Scripta Mater. 69 647
[22] Sepehri-Amin H, Ohkubo T, Nagashima S, Yano M, Shoji T, Kato A, Schrefl T, Hono K 2013 Acta Mater. 61 6622
[23] Sepehri-Amin H, Ohkubo T, Nishiuchi T, Hirosawa S, Hono K 2010 Scripta Mater. 63 1124
[24] Kronmller H, Durst K D, Sagawa M 1988 J. Magn. Magn. Mater. 74 291
[25] Hono K, Sepehri-Amin H 2012 Scripta Mater. 67 530
[26] Liu S, Kang N, Yu J, Kwon H, Lee J 2016 J. Magn. 21 51
[27] Li W F, Ohkubo T, Akiya T, Kato H Hono K 2009 J. Mater. Res. 24 413
[28] Sepehri-Amin H, Liu L H, Ohkubo T, Yano M, Shoji T, Kato A, Schrefl T, Hono K 2015 Acta Mater. 99 297
[29] Hirosawa S, Matsuura Y, Yamamoto H, Fujimura S, Sagawa M, Yamauchi H 1986 J. Appl. Phys. 59 873
[30] Haynes W M 2016 CRC Handbook of Chemistry and Physic (96th Ed.) (BOCA Raton:CRC Press) pp5-81-5-83
[31] Cui X G, Yan M, Ma T Y, Yu L Q 2008 Physica B 403 4182
[32] Sun C, Liu W Q, Sun H, Yue M, Yi X F, Chen J W 2012 J. Mater. Sci. Technol. 28 927
[33] He Q J, Li W 2001 Met. Funct. Mater. 8 8 (in Chinese) [贺琦军, 李卫 2001 金属功能材料 8 8]
[34] Liu W Q, Yue M, Zhang J X, Wang G P, Li T 2007 Rare Metal. Mat. Eng. 36 1066 (in Chinese) [刘卫强, 岳明, 张久兴, 王公平, 李涛 2007 稀有金属材料与工程 36 1066]
[35] Isotahdon E, Huttunen-Saarivirta E, Kuokkala V T, Paju M 2012 Mater. Chem. Phys. 135 762
-
[1] Xu T 2004 Chin. Rare Earths 25 31 (in Chinese) [许涛 2004 稀土 25 31]
[2] Chen Y H, Wang H Y, Pei Y C, Ren J, Wang J J 2015 ACS Sustain. Chem. Eng. 3 3167
[3] Saito T, Sato H, Motegi T 2006 J. Alloys Compd. 425 145
[4] Sepehri-Amin H, Ohkubo T, Zakotnik M, Prosperi D, Afiuny P, Tudor C O, Hono K 2017 J. Alloys Compd. 694 175
[5] Li X T, Yue M, Liu W Q, Li X L, Yi X F, Huang X L, Zhang D T, Chen J W 2015 J. Alloys Compd. 649 656
[6] Zakotnik M, Tudor C O 2015 Waste Manage. 44 48
[7] Li C, Liu W Q, Yue M, Liu Y Q, Zhang D T, Zuo T Y 2014 IEEE Trans. Magn. 50 2105403
[8] Kawasaki T, Itoh M, Ken-Ichi M 2003 Mater. Trans. 44 1682
[9] Ma T Y, Wang X J, Liu X L, Wu C, Yan M 2015 J. Phys. D:Appl. Phys. 48 215001
[10] Oono N, Sagawa M, Kasada R, Matsui H, Kimura A 2011 J. Magn. Magn. Mater. 323 297
[11] Suzuki H, Satsu Y, Komuro M 2009 J. Appl. Phys. 105 07A734
[12] Guo S, Zhang X F, Ding G F, Chen R J, Lee D, Yan A R 2014 J. Appl. Phys. 115 17A754
[13] Watanabe N, Itakura M, Kuwano N, Li D, Suzuki S, Ken-Ich M 2007 Mater. Trans. 48 915
[14] Soderžnik M, Korent M, Soderžnik K Ž, Katter M, stner K, Kobe S 2016 Acta Mater. 115 278
[15] Tang M H, Bao X Q, Lu K C, Lu S, Li J H, Gao X X 2016 Scripta Mater. 117 60
[16] Liang L P, Ma T Y, Pei Z, Jin J Y, Mi Y 2014 J. Magn. Magn. Mater. 355 131
[17] Ji W X, Liu W Q, Yue M, Zhang D T, Zhang J X 2015 Physica B 476 147
[18] Chen F G, Zhang T Q, Jing W, Zhang L T, Zhou G F 2015 Scripta Mater. 107 38
[19] Akiya T, Liu J, Sepehri-Amin H, Ohkubo T, Hioki K, Hattori A, Hono K 2014 J. Appl. Phys. 115 17A766
[20] Tang X, Chen R, Yin W, Wang J Z, Lee D, Yan A R 2013 Appl. Phys. Lett. 102 72409
[21] Sepehri-Amin H, Liu J, Ohkubo T, Hioki K, Hattori A, Hono K 2013 Scripta Mater. 69 647
[22] Sepehri-Amin H, Ohkubo T, Nagashima S, Yano M, Shoji T, Kato A, Schrefl T, Hono K 2013 Acta Mater. 61 6622
[23] Sepehri-Amin H, Ohkubo T, Nishiuchi T, Hirosawa S, Hono K 2010 Scripta Mater. 63 1124
[24] Kronmller H, Durst K D, Sagawa M 1988 J. Magn. Magn. Mater. 74 291
[25] Hono K, Sepehri-Amin H 2012 Scripta Mater. 67 530
[26] Liu S, Kang N, Yu J, Kwon H, Lee J 2016 J. Magn. 21 51
[27] Li W F, Ohkubo T, Akiya T, Kato H Hono K 2009 J. Mater. Res. 24 413
[28] Sepehri-Amin H, Liu L H, Ohkubo T, Yano M, Shoji T, Kato A, Schrefl T, Hono K 2015 Acta Mater. 99 297
[29] Hirosawa S, Matsuura Y, Yamamoto H, Fujimura S, Sagawa M, Yamauchi H 1986 J. Appl. Phys. 59 873
[30] Haynes W M 2016 CRC Handbook of Chemistry and Physic (96th Ed.) (BOCA Raton:CRC Press) pp5-81-5-83
[31] Cui X G, Yan M, Ma T Y, Yu L Q 2008 Physica B 403 4182
[32] Sun C, Liu W Q, Sun H, Yue M, Yi X F, Chen J W 2012 J. Mater. Sci. Technol. 28 927
[33] He Q J, Li W 2001 Met. Funct. Mater. 8 8 (in Chinese) [贺琦军, 李卫 2001 金属功能材料 8 8]
[34] Liu W Q, Yue M, Zhang J X, Wang G P, Li T 2007 Rare Metal. Mat. Eng. 36 1066 (in Chinese) [刘卫强, 岳明, 张久兴, 王公平, 李涛 2007 稀有金属材料与工程 36 1066]
[35] Isotahdon E, Huttunen-Saarivirta E, Kuokkala V T, Paju M 2012 Mater. Chem. Phys. 135 762
计量
- 文章访问数: 7095
- PDF下载量: 125
- 被引次数: 0