Dependence of magnetic, phase-transformation and microstructural characteristics on the Cu content of Nd-Fe-B sintered magnet
- Title
- Dependence of magnetic, phase-transformation and microstructural characteristics on the Cu content of Nd-Fe-B sintered magnet
- Author
- 김영도
- Keywords
- Nd-Fe-B sintered magnets; Cu content; Phase-transformation temperature; Post-sintering annealing; Nd-rich phase
- Issue Date
- 2014-03
- Publisher
- Elsevier Science LTD
- Citation
- ACTA MATERIALIA, 2014, 66, P.12-21
- Abstract
- We have investigated the changes in the magnetic, phase-transformation and microstructural properties of Nd-Fe-B sintered magnets as a function of Cu content (0.2-0.5 at.%). The coercivity decreased (28.7 -> 27.1 kOe) with increasing Cu content without changing the remanence of the magnets under the normal post-sintering annealing (PSA) conditions. Phase-transformation temperature changes of the magnet were observed as the Cu content of the magnet was increased. In the 0.2 at.% Cu magnet, the triple junction phase (TJP) and grain boundary phase (GBP), composed of the Cu-enriched C-Nd2O3 phase, were formed. However, in the 0.5 at.% Cu magnet, the TJP and GBP were composed of the h-Nd2O3 phase. By considering the dependence of Cu content on the phase transformation, we have modified the 1st-PSA temperature to recover the coercivity. Through our newly established PSA conditions, the TJP and GBP in the 0.5 at.% Cu magnet were formed as the C-Nd2O3 phase. As a result, the coercivity of the magnet was noticeably enhanced (27.1 -> 29.4 kOe). The reasons for the coercivity deterioration in the high-Cu-content magnet were clarified. The detailed mechanism of the microstructural and magnetic property improvements induced by the modified 1st-PSA condition is discussed. The critical role of Cu in the microstructural changes of Nd-rich TJP and GBP during the PSA is also analyzed based on these results. (C) 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
- URI
- https://www.sciencedirect.com/science/article/pii/S135964541300921X?via%3Dihubhttp://hdl.handle.net/20.500.11754/44122
- ISSN
- 1359-6454; 1873-2453
- DOI
- 10.1016/j.actamat.2013.11.063
- Appears in Collections:
- COLLEGE OF ENGINEERING[S](공과대학) > MATERIALS SCIENCE AND ENGINEERING(신소재공학부) > Articles
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