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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 flexural strength of Ce-Fe-B magnets was measured with a series of commercially available magnets (R 1-x Ce x) _ (30.5-31.5) Fe_ (bal.) B_1M_1 (mass fraction,%) , Fracture toughness, hardness and brittleness index. The microscopic fracture of the magnet was analyzed by SEM and EDS. The results show that the flexural strength and fracture toughness of Ce-containing magnets decrease with the increase of Ce content, and the variation of Vickers hardness with Ce content (x) is not obvious. When x = 0.15, the maximum mechanical properties of the magnets appear. The mechanical indexes such as flexural strength, fracture toughness and brittleness index of the magnets are obviously better than ordinary sintered Nd-Fe-B magnets. More magnets are found in this magnet, The “flocculent” oxide phase exists. The flocculent phase absorbs a part of energy during crack propagation and can relieve the stress concentration at the tip of the crack, thereby strengthening and toughening the flocculent phase, which is beneficial to improving the mechanical properties of the magnet. When the content of Ce in the magnet reaches x = 0.45, the mechanical properties of the magnet are remarkably deteriorated because of the presence of large grains in the magnet and significant deterioration of the microstructure of the magnet. The microscopic mechanism of fracture of different Ce content magnets is mainly intergranular fracture.