摘要
以不同Ce含量的系列商业磁体(R_(1-x)Ce_x)_(30.5~31.5)Fe_(bal.)B_1M_1(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。
The （R, Ce）-Fe-B magnets have been successfully industrialized in recent years. The me- chanical property of sintered permanent magnets is one important aspect of their comprehensive perfor- mances, 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 （Rl-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 （Rl_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/：ERE=45%）. That is probably because the microstructures of the magnet with x=0.45 become de- teriorated, 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.
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
2017年第11期1478-1486,共9页
Acta Metallurgica Sinica
基金
国家重点基础研究发展计划项目No.2014CB643701
国家自然科学基金重点项目No.51331003~~
关键词
烧结Ce-Fe-B磁体
力学性能
加工性能
断裂机理
sintered Ce-Fe-B magnet, mechanical property, machinable property,fracture mechanism
