IDEA #5LN9AM Development of sintered anisotropic nanostructured Nd-Fe-B magnets

Nanostructurization is one of the most promising methods used to improve the magnetic properties of permanent magnets. Nanostructured magnets will have enhanced energy product [1]. This effect is explained by the exchange interaction of highly dispersed one-domain grains of the magnetically hard and magnetically soft phases. Treatment under hydrogen atmosphere, hydrogen treatment, is one of the most efficient routes of nanocrystalline magnetic material formation. In particular fine-crystalline microstructure, anisotropic SmCo5 powders with high coercivity are obtained by this method [2-5]. This route was successfully used for treatment of Nd-Fe-B type magnets [6, 7]. It was shown [8-10] that sintering of nanocrystalline powders is possible at temperatures lower than 1000 °C. Now, it is necessary to optimize the parameters of the hydrogen treatment process for fabrication of anisotropic, nanocrystalline sintered magnets with high magnetic properties. The aim of the project is to optimize the hydrogen treatment process parameters of Nd2Fe14B type alloys for obtaining the anisotropic nanocrystalline powders and to optimize parameters of low temperature sintering of anisotropic nanocrystalline magnets. In other words, hydrogen treatment process parameters should be optimized for the achievement of the highest magnetic properties of anisotropic nanocrystalline powders and sintered magnets. The tasks of the project. 1. To optimize the parameters of alloy milling in hydrogen for the achievement of the highest texture of samples after powders compacting in the magnetic field. 2. To optimize the parameters of low temperature sintering of powders for achievement of the highest density and the finest-grained microstructure of sintered magnets. 3. To study the mutual dependence of magnetic properties and microstructures of sintered magnets and parameters of their production. The expected results. The laboratory technique of fabrication of anisotropic nanocrystalline sintered Nd-Fe-B magnets will be developed. Besides, the following will be done: 1) the optimal process parameters of hydrogen milling of the alloy – the planetary mill rotation speed, duration of milling, hydrogen pressure – will be found for achievement of the highest degree of texture of the green compacts; 2) the optimal process parameters of the orientation and pressing of powder for the achievement of the highest degree of texture will be established; 3) the optimal process parameters of low temperature sintering of magnets – temperature, duration of sintering – will be established for the achievement of the highest density, the finest microstructure and the higher magnetic properties of sintered magnets; 4) dependence of magnetic properties and microstructures of sintered magnets on their fabrication parameters will be studied. Expected significance. The laboratory technology of fabrication of the sintered, anisotropic, nanostructured Nd-Fe-B magnets with high magnetic properties will be the basis for the development of the similar industrial large-scale technology. Relationships between hydrogen treatment parameters and peculiarities of formation of the anisotropic nanostructure in Nd-Fe-B type alloys will be used for the development of the methods of anisotropic nanostructure formation in other rare-earth ferromagnetic alloys. The obtained data will be used for the development of the methods of fabrication of Nd2Fe14B/Fe, SmCo5/Fe-Co and Sm2Co17/Fe-Co nanocomposites as the next generation of permanent magnets with the highest magnetic properties. 1. Coehoorn R., de Mooij D. B., and de Waard C. J.Mag.Magn. Mater. – 1989. – 80. – P. 101–104. 2. Bulyk I. I., Panasyuk V. V., and Trostyanchyn A. M. Patent 96,810 (Ukraine). H 01 F 1/053; H 01 F 1/055; B 82 B 3/00. 3. Bulyk I. I., Trostyanchyn A. M., Dmytryshyn V. M., and Lyutyy P. Ya. Patent 102 899 (Ukraine) H 01 F 7/00, H 01 F 7/02, B 22 F 9/00. 4. Bulyk I. I. and Panasyuk V. V. Materials Science, V. 48, No.1. 2012, P. 1-11. 5. Bulyk I. I., Varyukhin V. N. , Tarenkov V. Y., Burkhovetskii V. V., S. L. Sidorov V. V.. Fizika i tekhnika vysokikh davlieniy // – 2013. – V. 23, # 4. – P. 67-82 (in Russian). 6. Bulyk I. I., Trostyanchyn A. M., Burkhovetskii V. V., Tarenkov V. Y.. Metallofizika i Noveishie Technologii. – 2014. – V. 36, # 7. – P. 903-916 (in Ukrainian). 7. Bulyk I. I., Trostyanchyn A. M., Lyutyy P. Ya., Burkhovetskii V. V. Patent 106 651 (Ukraine) H01F 1/057, H01F 1/00, H01F 41/00, B22F 9/00, B22F 9/04. 8. Xiaoya L., Yuping L., Lianxi H. J. Magn. Magn. Mater, – 2013. – V. 330. – P. 25-30. 9. Kim J. W., Kim S. H., Song S. Y., Kim Y. D. J. Alloys and Compounds. – 2013. – V. 551. – P. 180–184. 10. Bulyk I. I., unpublished results. Ihor I. Bulyk D.Sc., Leader of Group, Karpenko-Physico-Mechanical Institute of NAS of Ukraine, 5, Naukova Str., Lviv, Ukraine 79601 ihor.bulyk@gmail.com bulyk@ipm.lviv.ua www.ipm.lviv.ua