Consolidation of Nanocrystalline Nd-Fe-B Powder by Hydrostatic Extrusion at High Temperature

• Authors: T. Gizynski , W. Kaszuwara , M. Kulczyk , M. Leonowicz
• Languages of publication: EN

Abstracts

EN

Hydrostatic extrusion is a modern method of shaping material microstructure and properties. Hydrostatic extrusion can also be successfully used for consolidation of hard magnetic powders. The effect of extrusion temperature, within the range of 700-800°C, on the magnetic properties of the bulk, final product was studied. A commercial MQU-F42 powder, dedicated to hot pressing, was placed in copper capsules and initially cold compacted up to 60% of the theoretical density. Subsequently, the billet was heated in an oven to temperatures 700 and 800°C, respectively and subjected to hydrostatic extrusion. The extruded product had a form of a copper rod, with the Nd-Fe-B core, having 96% of theoretical density (true strain 1.85 after extrusion at 800°C). The extrusion process led to deterioration of the coercivity, for which coarsening of the Nd₂Fe₁₄B grains was blamed. In order to prove this hypothesis, the starting powder was annealed in a temperature range of 550-900°C for various times. The crystallite size, measured after annealing by the X-ray diffraction method, showed that with extension of time and elevation of the temperature the crystallite size increases, however the dominating parameter is the temperature. Correlation of the crystallite size with temperature indicates that when the crystallites are larger than 80 nm the magnetic properties dramatically decrease. Additionally, after HE at 800°C micrometric size Nd-rich phase appear in the microstructure. The Nd is squeezed from the grain boundary of the Nd₂Fe₁₄B phase leading to non-isolated grains, which also contributes to the deterioration of the coercivity.

Keywords

EN

75.50.Ww

Discipline

• 75.50.Ww: Permanent magnets(for magnets, see 07.55.Db in instruments)

• Publisher: Institute of Physics, Polish Academy of Sciences
• Journal: Acta Physica Polonica A
• Year: 2017
• Volume: 131
• Issue: 5
• Pages: 1260-1263

Dates

published

2017-05

Contributors

author

T. Gizynski

• Warsaw University of Technology, Faculty of Materials Science and Engineering, Wołoska 141, 02-507 Warsaw, Poland

author

W. Kaszuwara

• Warsaw University of Technology, Faculty of Materials Science and Engineering, Wołoska 141, 02-507 Warsaw, Poland

author

M. Kulczyk

• Institute of High Pressure Physics, Polish Academy of Sciences, Sokołowska 29/37, 01-142 Warsaw, Poland

author

M. Leonowicz

• Warsaw University of Technology, Faculty of Materials Science and Engineering, Wołoska 141, 02-507 Warsaw, Poland

References

• [1] W. Pachla, M. Kulczyk, A. Świderska-Środa, M. Lewandowska, H. Garbacz, A. Mazu, K.J. Kurzydłowski, in: Proc. 9th Int. Conf. on Mat. Forming ESAFORM-2006, Glasgow 2006, p. 535
• [2] W. Pachla, A. Morawski, P. Kovac, I. Husek, A. Mazur, T. Lada, R. Diduszko, T. Melisek, V. Strbık, M. Kulczyk, Supercond. Sci. Technol. 19, 1 (2006), doi: 10.1088/0953-2048/19/1/001
• [3] M. Sagawa, S. Fujimura, M. Togawa, Y. Matsuura, J. Appl. Phys. 55, 2083 (1984), doi: 10.1063/1.333572
• [4] W. Kaszuwara, M. Kulczyk, M. Leonowicz, T. Gizynski, B. Michalski, IEEE Trans. Magn. 50, 1 (2014), doi: 10.1109/TMAG.2014.2317152
• [5] G. Schneider, E.-T. Henig, G. Petzow, H.H. Stadelmaier, Z. Metallkde 77, 755 (1986)
• [6] D. Oleszak, A. Olszyna, Composites R4, 284 (2004)
• [7] T. Gizynski, W. Kaszuwara, P. Pawlik, M. Kulczyk, M. Leonowicz, B. Michalski, j.127{626{2015
• [8] Er. Girt, Kannan M. Krishnan, G. Thomas, E. Girt, Z. Altounian, J. Magn. Magn. Mater. 231, 219 (2001), doi: 10.1016/S0304-8853(01)00031-2

Identifiers

DOI

10.12693/APhysPolA.131.1260