Effect of Copper and Titanium Addition on Microstructures and Magnetic Properties of Sintered Nd22Fe71B7 Magnets
来源期刊:JOURNAL OF RARE EARTHS2001年第1期
论文作者:孙占波 杨森 孙军 王献辉 宋晓平
Abstract: Alloying elements Cu and Ti were added to the intergranular regions of sintered NdFeB magnets and their effects on microstructure and magnetic properties were investigated. The results show that small amounts of Cu/Ti additives can enhance the coercivity greatly and have little effect on the remanence of the magnets, while Ti content is less than 1.2%. The improvement of the coercivity can be attributed to the segregation of Cu and Ti on the surface of main phase, which inhibits the growth of main phase grains during sintering. At the same time, segregation of Cu and Ti can also prevent the magnetic coupling of Nd2Fe14B grains to a certain degree and impede effectively the propagation of reversed domain walls through the magnetic phase grains. As the Ti content increased above 1.2% a strip-like Ti-rich phase appears in the intergranular region, resulting in the dramatic reduction of the remanence of Nd-Fe-B magnets. Compared with the single alloying method, the combined alloying of intergranular regions is more efficient to modify the properties of NdFeB magnets.
孙占波1,杨森1,孙军1,王献辉1,宋晓平1
(1.School of Materials Science and Engineering, Xi′an Jiaotong University,)
Abstract:Alloying elements Cu and Ti were added to the intergranular regions of sintered NdFeB magnets and their effects on microstructure and magnetic properties were investigated. The results show that small amounts of Cu/Ti additives can enhance the coercivity greatly and have little effect on the remanence of the magnets, while Ti content is less than 1.2%. The improvement of the coercivity can be attributed to the segregation of Cu and Ti on the surface of main phase, which inhibits the growth of main phase grains during sintering. At the same time, segregation of Cu and Ti can also prevent the magnetic coupling of Nd2Fe14B grains to a certain degree and impede effectively the propagation of reversed domain walls through the magnetic phase grains. As the Ti content increased above 1.2% a strip-like Ti-rich phase appears in the intergranular region, resulting in the dramatic reduction of the remanence of Nd-Fe-B magnets. Compared with the single alloying method, the combined alloying of intergranular regions is more efficient to modify the properties of NdFeB magnets.
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