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Open AccessArticle

In situ Observation of Phase Transformation in MnAl(C) Magnetic Materials

Powder & Ceramic Division, Korea Institute of Materials Science, Changwon, Gyeongnam 51508, Korea
College of Materials Science and Engineering, China Jiliang University, Hangzhou 310018, China
Authors to whom correspondence should be addressed.
Materials 2017, 10(9), 1016;
Received: 10 August 2017 / Revised: 25 August 2017 / Accepted: 29 August 2017 / Published: 31 August 2017
(This article belongs to the Section Structure Analysis and Characterization)
The phase transformation in two modes, including both displacive and massive growth of τ-phase from ε-MnAl(C), was observed by in situ transmission electron microscopy. The exact temperature range for different phase transformation modes was determined by magnetic measurements. The displacive growth of ε→τ in Mn54Al46 (or Mn54Al46C2.44) occurs at temperatures below 650 K (or 766 K), above which both modes coexist. One-third or less of the ε-phase can be transformed into τ-phase via displacive mode while the remaining two-thirds or more via massive mode. In bulk τ-phase, most τ-nanocrystals formed via displacive mode are distributed in the matrix of large τ-grains that formed via massive mode. The typical massive growth rate of the τ-phase is 8–60 nm/s, while the displacive growth rate is low. A more complete understanding of the ε→τ phase transformations in the MnAl-based magnets was provided in this work, based on which the annealing process for ε→τ was optimized and thus high purity τ-phase with high saturation magnetization was obtained. View Full-Text
Keywords: phase transformation; MnAl; Mn54Al46; MnAlC; diffusion; magnetic properties phase transformation; MnAl; Mn54Al46; MnAlC; diffusion; magnetic properties
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MDPI and ACS Style

Si, P.-Z.; Qian, H.-D.; Choi, C.-J.; Park, J.; Han, S.; Ge, H.-L.; Shinde, K.P. In situ Observation of Phase Transformation in MnAl(C) Magnetic Materials. Materials 2017, 10, 1016.

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