Phase Transitions in Mechanically Milled Mn-Al-C Permanent Magnets
Mn-Al powders were prepared by rapid solidification followed by high-energy mechanical milling. The rapid solidification resulted in single-phase ε. The milling was performed in both the ε phase and the τ phase, with the τ-phase formation accomplished through a heat treatment at 500 °C for 10 min. F...
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MDPI AG
2014-04-01
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| Series: | Metals |
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| Online Access: | http://www.mdpi.com/2075-4701/4/2/130 |
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doaj-0f10b3e24b534472a54ede594862cfe72020-11-24T22:07:59ZengMDPI AGMetals2075-47012014-04-014213014010.3390/met4020130met4020130Phase Transitions in Mechanically Milled Mn-Al-C Permanent MagnetsMichael J. Lucis0Timothy E. Prost1Xiujuan Jiang2Meiyu Wang3Jeffrey E. Shield4Department of Mechanical and Materials Engineering and Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, NE 68588, USADepartment of Mechanical and Materials Engineering and Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, NE 68588, USADepartment of Mechanical and Materials Engineering and Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, NE 68588, USADepartment of Mechanical and Materials Engineering and Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, NE 68588, USADepartment of Mechanical and Materials Engineering and Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, NE 68588, USAMn-Al powders were prepared by rapid solidification followed by high-energy mechanical milling. The rapid solidification resulted in single-phase ε. The milling was performed in both the ε phase and the τ phase, with the τ-phase formation accomplished through a heat treatment at 500 °C for 10 min. For the ε-milled samples, the conversion of the ε to the τ phase was accomplished after milling via the same heat treatment. Mechanical milling induced a significant increase in coercivity in both cases, reaching 4.5 kOe and 4.1 kOe, respectively, followed by a decrease upon further milling. The increase in coercivity was the result of grain refinement induced by the high-energy mechanical milling. Additionally, in both cases a loss in magnetization was observed. Milling in the ε phase showed a smaller decrease in the magnetization due to a higher content of the τ phase. The loss in magnetization was attributed to a stress-induced transition to the equilibrium phases, as no site disorder or oxidation was observed. Surfactant-assisted milling in oleic acid also improved coercivity, but in this case values reached >4 kOe and remained stable at least through 32 h of milling.http://www.mdpi.com/2075-4701/4/2/130permanent magnetsmechanical milling |
| collection |
DOAJ |
| language |
English |
| format |
Article |
| sources |
DOAJ |
| author |
Michael J. Lucis Timothy E. Prost Xiujuan Jiang Meiyu Wang Jeffrey E. Shield |
| spellingShingle |
Michael J. Lucis Timothy E. Prost Xiujuan Jiang Meiyu Wang Jeffrey E. Shield Phase Transitions in Mechanically Milled Mn-Al-C Permanent Magnets Metals permanent magnets mechanical milling |
| author_facet |
Michael J. Lucis Timothy E. Prost Xiujuan Jiang Meiyu Wang Jeffrey E. Shield |
| author_sort |
Michael J. Lucis |
| title |
Phase Transitions in Mechanically Milled Mn-Al-C Permanent Magnets |
| title_short |
Phase Transitions in Mechanically Milled Mn-Al-C Permanent Magnets |
| title_full |
Phase Transitions in Mechanically Milled Mn-Al-C Permanent Magnets |
| title_fullStr |
Phase Transitions in Mechanically Milled Mn-Al-C Permanent Magnets |
| title_full_unstemmed |
Phase Transitions in Mechanically Milled Mn-Al-C Permanent Magnets |
| title_sort |
phase transitions in mechanically milled mn-al-c permanent magnets |
| publisher |
MDPI AG |
| series |
Metals |
| issn |
2075-4701 |
| publishDate |
2014-04-01 |
| description |
Mn-Al powders were prepared by rapid solidification followed by high-energy mechanical milling. The rapid solidification resulted in single-phase ε. The milling was performed in both the ε phase and the τ phase, with the τ-phase formation accomplished through a heat treatment at 500 °C for 10 min. For the ε-milled samples, the conversion of the ε to the τ phase was accomplished after milling via the same heat treatment. Mechanical milling induced a significant increase in coercivity in both cases, reaching 4.5 kOe and 4.1 kOe, respectively, followed by a decrease upon further milling. The increase in coercivity was the result of grain refinement induced by the high-energy mechanical milling. Additionally, in both cases a loss in magnetization was observed. Milling in the ε phase showed a smaller decrease in the magnetization due to a higher content of the τ phase. The loss in magnetization was attributed to a stress-induced transition to the equilibrium phases, as no site disorder or oxidation was observed. Surfactant-assisted milling in oleic acid also improved coercivity, but in this case values reached >4 kOe and remained stable at least through 32 h of milling. |
| topic |
permanent magnets mechanical milling |
| url |
http://www.mdpi.com/2075-4701/4/2/130 |
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AT michaeljlucis phasetransitionsinmechanicallymilledmnalcpermanentmagnets AT timothyeprost phasetransitionsinmechanicallymilledmnalcpermanentmagnets AT xiujuanjiang phasetransitionsinmechanicallymilledmnalcpermanentmagnets AT meiyuwang phasetransitionsinmechanicallymilledmnalcpermanentmagnets AT jeffreyeshield phasetransitionsinmechanicallymilledmnalcpermanentmagnets |
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