Computational thermodynamics and microstructure simulations to understand the role of grain boundary phase in Nd-Fe-B hard magnets
To control the coercivity of Nd hard magnets efficiently, the thermal stability of constituent phases and the microstructure changes observed in hard magnets during thermal processes should be understood. Recently, the CALPHAD method and phase-field method have been recognized as promising approache...
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Online Access: | http://dx.doi.org/10.1080/14686996.2020.1859339 |
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doaj-e4779b25e3ff434ba1e21042ba70f6c12021-07-15T13:10:31ZengTaylor & Francis GroupScience and Technology of Advanced Materials1468-69961878-55142021-12-0122111310.1080/14686996.2020.18593391859339Computational thermodynamics and microstructure simulations to understand the role of grain boundary phase in Nd-Fe-B hard magnetsToshiyuki Koyama0Yuhki Tsukada1Taichi Abe2Graduate School of Engineering, Nagoya UniversityGraduate School of Engineering, Nagoya UniversityComputational Structural Materials Group, Research Center for Structural Materials, National Institute for Materials ScienceTo control the coercivity of Nd hard magnets efficiently, the thermal stability of constituent phases and the microstructure changes observed in hard magnets during thermal processes should be understood. Recently, the CALPHAD method and phase-field method have been recognized as promising approaches to realize phase stability and microstructure developments in engineering materials. Thus, we applied these methods to understand the thermodynamic feature of the grain boundary phase and the microstructural developments in Nd-Fe-B hard magnets. The results are as follows. (1) The liquid phase is a promising phase for covering the Nd2Fe14B grains uniformly. (2) The metastable phase diagram of the Fe-Nd-B ternary system suggests that the tie line end of the liquid phase changes drastically depending on the average composition of Nd. (3) The Nd concentration in the grain boundary phase can reach 100 at% if the volume fraction of the grain boundary phase is constrained. (4) The effect of Cu addition to the Nd-Fe-B system on the microstructural morphology is reasonably modeled based on the phase-field method. (5) The morphology of the liquid phase can be controlled using phase separation in the liquid phase and the grain size of the Nd2Fe14B phase.http://dx.doi.org/10.1080/14686996.2020.1859339phase transformationphase diagramcalphad methodphase-field method |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Toshiyuki Koyama Yuhki Tsukada Taichi Abe |
spellingShingle |
Toshiyuki Koyama Yuhki Tsukada Taichi Abe Computational thermodynamics and microstructure simulations to understand the role of grain boundary phase in Nd-Fe-B hard magnets Science and Technology of Advanced Materials phase transformation phase diagram calphad method phase-field method |
author_facet |
Toshiyuki Koyama Yuhki Tsukada Taichi Abe |
author_sort |
Toshiyuki Koyama |
title |
Computational thermodynamics and microstructure simulations to understand the role of grain boundary phase in Nd-Fe-B hard magnets |
title_short |
Computational thermodynamics and microstructure simulations to understand the role of grain boundary phase in Nd-Fe-B hard magnets |
title_full |
Computational thermodynamics and microstructure simulations to understand the role of grain boundary phase in Nd-Fe-B hard magnets |
title_fullStr |
Computational thermodynamics and microstructure simulations to understand the role of grain boundary phase in Nd-Fe-B hard magnets |
title_full_unstemmed |
Computational thermodynamics and microstructure simulations to understand the role of grain boundary phase in Nd-Fe-B hard magnets |
title_sort |
computational thermodynamics and microstructure simulations to understand the role of grain boundary phase in nd-fe-b hard magnets |
publisher |
Taylor & Francis Group |
series |
Science and Technology of Advanced Materials |
issn |
1468-6996 1878-5514 |
publishDate |
2021-12-01 |
description |
To control the coercivity of Nd hard magnets efficiently, the thermal stability of constituent phases and the microstructure changes observed in hard magnets during thermal processes should be understood. Recently, the CALPHAD method and phase-field method have been recognized as promising approaches to realize phase stability and microstructure developments in engineering materials. Thus, we applied these methods to understand the thermodynamic feature of the grain boundary phase and the microstructural developments in Nd-Fe-B hard magnets. The results are as follows. (1) The liquid phase is a promising phase for covering the Nd2Fe14B grains uniformly. (2) The metastable phase diagram of the Fe-Nd-B ternary system suggests that the tie line end of the liquid phase changes drastically depending on the average composition of Nd. (3) The Nd concentration in the grain boundary phase can reach 100 at% if the volume fraction of the grain boundary phase is constrained. (4) The effect of Cu addition to the Nd-Fe-B system on the microstructural morphology is reasonably modeled based on the phase-field method. (5) The morphology of the liquid phase can be controlled using phase separation in the liquid phase and the grain size of the Nd2Fe14B phase. |
topic |
phase transformation phase diagram calphad method phase-field method |
url |
http://dx.doi.org/10.1080/14686996.2020.1859339 |
work_keys_str_mv |
AT toshiyukikoyama computationalthermodynamicsandmicrostructuresimulationstounderstandtheroleofgrainboundaryphaseinndfebhardmagnets AT yuhkitsukada computationalthermodynamicsandmicrostructuresimulationstounderstandtheroleofgrainboundaryphaseinndfebhardmagnets AT taichiabe computationalthermodynamicsandmicrostructuresimulationstounderstandtheroleofgrainboundaryphaseinndfebhardmagnets |
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1721300977706860544 |