Microstructure and corrosion resistance of sintered Nd15Dy1.2Fe77Al0.8B6 and Nd22Fe71B7 magnets modified by intergranular addition of MgO and ZnO were investigated. Both the remanence and sintering density of the magnets increased slightly with intergranular additions of MgO and ZnO. There was a remarkable increase in coercivity of Nd22Fe71B7 after addition. Besides, the effects on magnetic properties and an improved corrosion resistance were observed. Compared with the native magnets without addition, corrosion potential of the magnets with MgO and ZnO additives was more positive and the current density in the anodic branch of the polarization curve was reduced. Corrosion resistance resulting from autoclave testing (2×105 Pa of steam pressure, 120 °C) showed that the corrosion rate of NdFeB magnets reduced with the increase of additive amount. Microstructure observation revealed that MgO and ZnO additives were incorporated into the intergranular phases in the magnets. With the introduction of MgO and ZnO, more intergranular phase with high oxygen content was formed while keeping the volume fraction of all the intergranular phases almost unchanged, which may contribute to improved corrosion resistance. Furthermore, addition of MgO and ZnO refined the grain size of Nd22Fe71B7.
参考文献
| [1] | Shinba Y;Konno TJ;Ishikawa K;Hiraga K;Sagawa M .Transmission electron microscopy study on Nd-rich phase and grain boundary structure of Nd-Fe-B sintered magnets[J].Journal of Applied Physics,2005(5):3504-1-3504-8-0. |
| [2] | Jiang Jianhua;Zeng Zhenpeng;Yu Jian;Wu Jiansheng Tokunaga M.The effect of Co addition on the fracture strength of NdFeB sintered magnets[J].Intermetallics,2001(09):269. |
| [3] | Fidler J.;Schrefl T. .OVERVIEW OF ND-FE-B MAGNETS AND COERCIVITY[J].Journal of Applied Physics,1996(8 Pt.2a):5029-5034. |
| [4] | Cheng Wenhao;Li Wei;Li Chuanjian;Dong Shengzhi .The magnetic properties,thermal stability and microstructure of Nd-Fe-B/Ga sintered magnets prepared by blending method[J].Journal of Magnetism and Magnetic Materials,2001,234:274. |
| [5] | Ghandehari M H .Reactivity of Dy2O3 and Tb4O7 with Nd15 Fe77B8 powder and the coercivity of the sintered magnets[J].Applied Physics Letters,1986,48:548. |
| [6] | Chen Zhongmin;Yan Aru;Wang Xiaotian .Improvement of magnetic properties and intergranular microstructure of Nd-Fe-B magnets by intergranular addition of MgO oxide[J].Journal of Applied Physics,1997,81:4456. |
| [7] | Chen Zhongmin;Yan Aru;Wang Xiaotian .Effects of intergranular additions of oxides on the coercivity,thermal stability and microstructure of Nd-Fe-B magnets[J].Journal of Magnetism and Magnetic Materials,1996,162:307. |
| [8] | Kim A.S.;Camp F.E. .Effect of oxygen, carbon, and nitrogen contents on the corrosion resistance of Nd-Fe-B magnets[J].IEEE Transactions on Magnetics,1990(5):1936-1938. |
| [9] | Camp F E;Kim A S .Effect of microstructure on the corrosion behavior of NdFeB and NdFeCoAlB magnets[J].Journal of Applied Physics,1991,70:6348. |
| [10] | Shrefl T;Schmidts H F;Fidler J;Kronmüler H .The role of exchange and dipolar coupling at grain boundaries in hard magnetic materials[J].Journal of Magnetism and Magnetic Materials,1993,124:251. |
| [11] | Warren G W;Gao G;Li Q .Corrosion of NdFeB permanent magnet materials[J].Journal of Applied Physics,1991,70:6609. |
| [12] | Jacobson J;Kim A .Oxidation behavior of Nd-Fe-B magnets[J].Journal of Applied Physics,1987,61:3763. |
| [13] | Zheng Jingwu;Jiang Liqiang;Qiao Liang;Lin Min .Refinement of melt-spun quenching NdFeB powders by ball milling[J].Journal of Rare Earths,2006,24:211. |
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