Microstructure, coercivity and thermal stability of nanostructured (Nd,Ce)-(Fe,Co)-B hot-compacted permanent magnets

Accelerated discovery of cost-effective Nd–Fe–B magnets through adaptive learning

“…is doped into the Nd–Fe–B system, not all of the doping species enter the main phase. Instead, a significant portion of them enters the grain boundary region, forming RE-rich grain boundary phases along with Nd/Fe, such as REFe 2 , RE(Fe, Co) 4 B, etc 33 . This partitioning behavior, namely, the partitioning of a doping species in the Nd 2 Fe 14 B main phase and Nd-rich grain boundary phase, has significant implications for the magnetic property of the resulting Nd–Fe–B.…”

“…[22][23][24][25][26][27][28][29] Co, with a very high T C , could signicantly improve the temperature stability and therefore benet HT magnetic properties, although it results in loss of RT magnetic properties as well. 21,[30][31][32][33] In recent years, investigation of Y as a promising doping species for Nd-Fe-B has picked up momentum. Although Y fails to rise above La and Ce in terms of M r and H a , a Advanced Engineering Research Division, Toyota Motor Technical Research And Service (Shanghai) Co., Ltd, China.…”

“…22–29 Co, with a very high T C , could significantly improve the temperature stability and therefore benefit HT magnetic properties, although it results in loss of RT magnetic properties as well. 21,30–33 In recent years, investigation of Y as a promising doping species for Nd–Fe–B has picked up momentum. Although Y fails to rise above La and Ce in terms of M r and H a , Y 2 Fe 14 B demonstrates a higher T C than La 2 Fe 14 B or Ce 2 Fe 14 B, as well as a positive temperature coefficient of H a over a wide temperature range, rendering it a promising candidate for enhanced HT magnetic properties.…”

The Effect of Grain Size on the Diffusion Efficiency and Microstructure of Sintered Nd-Fe-B Magnets by Tb Grain Boundary Diffusion

“…Nd-Fe-B-based sintered magnets are widely used in many magnetic devices such as traction motors for hybrid or electronic vehicles and wind generators because of their excellent magnetic properties of high remanence and magnetic energy product [ 1 , 2 , 3 ]. However, the coercivity of the actual magnet is far below the intrinsic anisotropy field of the Nd 2 Fe 14 B phase (~7.3T), which has become the key factor limiting the application of Nd-Fe-B magnets [ 2 , 3 , 4 ]. In order to enhance the coercivity of sintered Nd-Fe-B magnets, the introduction of heavy rare earth (HRE, such as Dy and Tb) elements is an effective method due to the higher anisotropy fields of HRE 2 Fe 14 B phases.…”

Study on temperature stability and mechanical properties of sintered Nd_25.5Dy_6.5Co₁₃(Fe, M)_balB_0.98 magnet

“…~100 ℃，剩磁温度系数 α 约为-0.09~-0.12 %/℃) ，致使其在高温电机、精密仪表 等领域的应用受到了很大的限制 [7][8][9] 。2:17 型 Sm-Co 磁体虽然具有良好温度稳定 性，剩磁温度系数约为-0.03~-0.04 %/℃(室温~100 ℃) ，但是存在磁能积较低和 力学性能较差的问题 [10][11][12] 。因此开发具有高磁性能、高温度稳定性的 Nd-Fe-B 磁 体具有重要的现实意义。 研究表明 [13,14] 取代 Nd，可形成具有高的磁晶各向异性场 H A 的 HRE 2 Fe 14 B 主相，因而可以提高 磁体的矫顽力 [15][16][17] ；在 HRE 2 Fe 14 B 主相中，重稀土原子磁矩与 Fe 原子磁矩反平 行排列，在-100 ℃~ +200 ℃温度区间内，饱和磁化强度 M S 随温度升高而升高， 即温度系数为正，这与 Nd 2 Fe 14 B 趋势相反，因此重稀土元素的添加可以降低剩 磁温度系数 [18,19] 。然而，HRE 2 Fe 14 B 主相的饱和磁化强度 M S 较低，过多的添加 会不可避免的带来磁能积的降低。Li 等 [20] 通过铸锭+球磨工艺的制备了成分为 (Nd 0.6 Dy 0.4 ) 16 (Fe 0.7 Co 0.3 ) 78 B 6 的烧结 Nd-Fe-B 磁体，剩磁温度系数 α=-0.028 %/℃ (20-100℃) ， 剩磁 B r =9.5 kGs， 矫顽力 H cj =15 kOe， 最大磁能积(BH) max =20 MGOe。 Kablov 等 [21] 研究表明(Nd 0.52 Dy 0.48 ) 15 添加将会影响磁体的力学性能 [22][23][24][25] ，而对于同时含有较多 Dy 和 Co 磁体的力学 性能尚无相关报道。 本文同时添加 6.5 wt.%的 Dy 和 13 wt.%的 Co 部分取代 Nd 和 Fe，采用速 相关研究指出，晶界中的 1:3 相可能是一种铁磁相 [29,30] ，降低晶界相的去磁耦合…”