双合金法Dy含量对NdFeB烧结磁体结构和磁性能的影响
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摘要
采用双合金工艺制备烧结NdFeB磁体,研究富Dy辅合金添加对烧结NdFeB磁体性能的影响。研究表明,310℃脱氢制备的(PrNd)19Dy23(FeCoCuGa)bal B1富Dy辅合金,可保留高Dy富稀土相的氢,降低高Dy富稀土相熔点,在1070℃烧结,不同Dy含量的磁体密度均在7.54 g/cm3以上。其磁体综合性能远高于550℃脱氢制备的富Dy辅合金添加磁体和单合金法磁体。通过310℃脱氢制备富Dy辅合金添加方法制备磁体可以调控磁体主相和富稀土相成分,使绝大多数主相颗粒中不含Dy,保持较高的剩磁,使少部分主相中含较高的Dy,保持高矫顽力;另一方面,310℃脱氢富Dy辅合金中高Dy氢化物富稀土相的Dy在烧结过程中扩散进入主相,在主相边界形成核-壳结构,提高磁体的矫顽力,同时保持较高的剩磁。
Sintered NdFeB magnet was prepared by double alloy process, and the Ifluence of Dy-rich auxiliary alloy content on its magnetic properties was studied. Research shows that when(PrNd)19 Dy23(FeCoCuGa) bal B1 Dy-rich auxiliary alloy was dehydrogenized at 310 ℃, hydrogen in rare earth-rich phase with high Dy in Dy-rich auxiliary alloy can be retain, reducing the melting point of rare earth-rich phase with high Dy. So the density of magnet with different Dy content was above 7.54 g/m3 at sintering temperature 1070 ℃. The comprehensive magnetic properties were much higher than those of magnets with(PrNd)19 Dy23(FeCoCuGa) bal B1 addition dehydrogenated at 550 ℃ and prepared by single alloy method. The preparation method of magnet with added Dy-rich auxiliary alloy dehydrogenated at 310 ℃ can control the ingredients of main and rare earth rich phase, resulting in vast number of main phase particles without Dy for maintaining high remanence, small part of the main phase with high content of Dy for maintaining high coercivity; on the other hand, Dy of rare earth-rich phase with high Dy in Dy-rich auxiliary alloy diffuses into the main phase in the sintering process and resultantly "core shell" structure is formed, improving the coercivity while maintaining high remanence.
Sintered NdFeB magnet was prepared by double alloy process, and the Ifluence of Dy-rich auxiliary alloy content on its magnetic properties was studied. Research shows that when(PrNd)19 Dy23(FeCoCuGa) bal B1 Dy-rich auxiliary alloy was dehydrogenized at 310 ℃, hydrogen in rare earth-rich phase with high Dy in Dy-rich auxiliary alloy can be retain, reducing the melting point of rare earth-rich phase with high Dy. So the density of magnet with different Dy content was above 7.54 g/m3 at sintering temperature 1070 ℃. The comprehensive magnetic properties were much higher than those of magnets with(PrNd)19 Dy23(FeCoCuGa) bal B1 addition dehydrogenated at 550 ℃ and prepared by single alloy method. The preparation method of magnet with added Dy-rich auxiliary alloy dehydrogenated at 310 ℃ can control the ingredients of main and rare earth rich phase, resulting in vast number of main phase particles without Dy for maintaining high remanence, small part of the main phase with high content of Dy for maintaining high coercivity; on the other hand, Dy of rare earth-rich phase with high Dy in Dy-rich auxiliary alloy diffuses into the main phase in the sintering process and resultantly "core shell" structure is formed, improving the coercivity while maintaining high remanence.
引文
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[4]Gao R W,Li H,Jiang S T,et al.Investigations on magnetization reversal processes in oriented sintered Nd-Fe-B alloys[J].J Magn Magn Mater,1991,95:205.
[5]Kianvash A,Mottram R S,Harris I R.Densification of a Nd13Fe78NbCoB7-type sintered magnet by(Nd,Dy)-hydride additions using a powder blending technique[J].JAlloys Compds,1999,287:206.
[6]周寿增,董清飞,高学绪.稀土永磁材料与技术[M].北京:冶金工业出版社,2012.217-218.
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