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金属学报  2017, Vol. 53 Issue (11): 1478-1486    DOI: 10.11900/0412.1961.2016.00556
  研究论文 本期目录 | 过刊浏览 |
李安华1(), 张月明1, 冯海波1, 邹宁2, 吕忠山2, 邹旭杰2, 李卫1
1 钢铁研究总院功能材料研究所 北京 100081
2 宁波复能新材料有限公司 宁波 315336
Mechanical Properties of Sintered Ce-Fe-B Magnets
Anhua LI1(), Yueming ZHANG1, Haibo FENG1, Ning ZOU2, Zhongshan LÜ2, Xujie ZOU2, Wei LI1
1 Division of Functional Material, Central Iron & Steel Research Institute, Beijing 100081, China
2 Ningbo Funeng New Material Company, Ningbo 315336, China
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以不同Ce含量的系列商业磁体(R1-xCex)30.5~31.5Febal.B1M1 (质量分数,%)为研究对象,测试Ce-Fe-B磁体的抗弯强度、断裂韧性、硬度及脆性指数等性能,并对磁体的微观断口进行SEM和EDS分析。结果表明,含Ce磁体的抗弯强度和断裂韧性随Ce含量的增加呈减小的趋势,其Vickers硬度随Ce含量(x)的变化规律不明显。当x=0.15时,磁体力学性能出现极大值,磁体的抗弯强度、断裂韧性及脆性指数等力学指标均明显优于普通烧结Nd-Fe-B磁体;在此磁体中发现较多的“絮状”氧化物相存在,絮状相在裂纹扩展过程中会吸收一部分能量,可以缓解裂纹尖端的应力集中状态,因而起到强化和韧化的作用,对提高磁体的力学性能有利。当磁体中的Ce含量达到x=0.45时,磁体的力学性能明显变差,这是因为:此时磁体中有大晶粒出现,磁体的微观结构明显劣化。不同Ce含量磁体的断裂微观机制主要为沿晶断裂。

关键词 烧结Ce-Fe-B磁体力学性能加工性能断裂机理    

The (R, Ce)-Fe-B magnets have been successfully industrialized in recent years. The mechanical property of sintered permanent magnets is one important aspect of their comprehensive performances, which directly influences the service reliability and the production cost. In this work, the bending strength, fracture toughness, Vickers hardness and brittleness index of commercial (R1-xCex)30.5’31.5Febal.-B1M1 (mass fraction, %) magnets with different Ce contents have been investigated. The microfractures of the magnets were observed by SEM equipped with EDS. It shows that the bending strength and the fracture toughness of (R, Ce)-Fe-B magnets have a downward tendency with increasing Ce content x, while the Vickers hardness of the magnets varies irregularly with Ce content. The optimum mechanical properties have been obtained in the (R1-xCex)30.5~31.5Febal.-B1M1 magnet with x=0.15; the bending strength, fracture toughness and brittleness index of the magnet with x=0.15 are obviously superior to those of the ordinary sintered Nd-Fe-B magnets. Some flocculent oxide phases have been discovered in the (R, Ce)-Fe-B magnet with x=0.15. The flocculent phases may absorb part of energy during crack propagating, and reduce the stress concentration at a crack tip, which is beneficial to strengthening and toughening of (R, Ce)-Fe-B magnets. However, the mechanical properties are obviously worse for the magnet with x=0.45 (Ce/ΣRE=45%). That is probably because the microstructures of the magnet with x=0.45 become deteriorated, in which abnormally large grains have been observed. The results confirm that the fracture mechanism of sintered (R, Ce)-Fe-B magnets with different Ce contents mainly appears intergranular fracture.

Key wordssintered Ce-Fe-B magnet    mechanical property    machinable property    fracture mechanism
收稿日期: 2016-12-13      出版日期: 2017-06-23
:  TG146.4  
基金资助:国家重点基础研究发展计划项目 No.2014CB643701和国家自然科学基金重点项目No.51331003

作者简介 李安华,女,1975年生,教授,博士


李安华, 张月明, 冯海波, 邹宁, 吕忠山, 邹旭杰, 李卫. 烧结Ce-Fe-B磁体的力学性能[J]. 金属学报, 2017, 53(11): 1478-1486.
Anhua LI, Yueming ZHANG, Haibo FENG, Ning ZOU, Zhongshan LÜ, Xujie ZOU, Wei LI. Mechanical Properties of Sintered Ce-Fe-B Magnets. Acta Metall, 2017, 53(11): 1478-1486.

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图1  磁体抗弯实验和断裂韧性实验示意图
x Br / T Hcj / (kAm-1) Hk / (kAm-1) (BH)max / (kJm-3) Hk /Hcj ρ / (gm-3)
0* 1.27 1630 1547 313 0.95 7.538
0.15 1.32 959 940 335 0.98 7.557
0.30 1.22 1012 964 279 0.95 7.604
0.35 1.17 926 883 252 0.95 7.607
0.40 1.13 910 888 234 0.98 7.617
0.45 1.10 801 752 222 0.94 7.632
表1  烧结(R1-xCex)30.5~31.5Febal.B1M1磁体的磁性能和密度
图2  烧结(R, Ce)-Fe-B磁体抗弯实验的典型载荷-位移曲线
x Rbb / MPa KIC / (MPam1/2) Hv / MPa Hv/KIC / μm-1/2
0 321 3.66 5704 1.56
0.15 394 4.48 5606 1.25
0.3 356 3.83 5782 1.51
0.35 304 3.29 5900 1.79
0.40 306 3.56 5566 1.56
0.45 257 3.27 5753 1.76
表2  烧结(R1-xCex)30.5~31.5Febal.B1M1磁体的力学性能
图3  烧结(R1-xCex)30.5~31.5Febal.B1M1磁体抗弯断口的典型微观形貌
x Atomic fraction / %
O Fe Ce Nd Zr
0.15 65.31 32.45 2.24 - -
0.30 69.69 25.41 4.90 - -
0 28.60 66.59 - 3.72 1.09
表3  实验磁体中氧化物相的EDS分析结果
图4  Ce-Fe-B磁体抗弯试样断口形貌的HRSEM像
图5  实验磁体中氧化物相的EDS谱
图6  烧结(R0.55Ce0.45)30.5~31.5Febal.B1M1磁体的SEM微观结构和断口形貌
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