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Microstructure Observation of Oxidation of Nd-Magnet at High Temperatures

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Rare Metal Technology 2017

Part of the book series: The Minerals, Metals & Materials Series ((MMMS))

Abstract

There is a growing interest in recycling/recovery of rare earth elements from permanent magnets. A number of processing techniques are currently being developed but highly sensitive to the oxidation state of rare earth in the magnetic waste. This study investigated the microstructural changes of thermal oxidation of an Nd-based magnet and the behaviour of its oxides under high temperature recycling/recovery process. XRD analyses were carried out on a powdered sample (~10 µm) heated to 1273 K. SEM-EDS analysis was conducted on the heated bulk samples to provide detailed metallographic information. Metallographic analysis revealed multiple oxidation zones where the outer scale did not effectively inhibit further diffusion of oxygen. The thickness of this scale was found to be grown quite rapidly at temperatures higher than 973 K. The results indicated that the micro-mechanism of oxidation at higher temperature are more complex than at temperature below 773 K.

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Acknowledgements

The authors are grateful to the CSIRO Minerals Resources for the financial support (top up scholarship for Mr Muhamad Firdaus) for this work. The authors would like to also thanks Dr. Mark Pownceby for the SEM analysis at CSIRO.

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Authors and Affiliations

  1. Department of Mechanical and Product Design, Swinburne University of Technology, Melbourne, VIC, 3122, Australia

    Muhamad Firdaus, M. Akbar Rhamdhani & Yvonne Durandet

  2. CSIRO Mineral Resources, Private Bag 10, Clayton South, VIC, 3169, Australia

    Muhamad Firdaus, W. John Rankin, Kathie Mcgregor & Nathan A.S. Webster

Authors
  1. Muhamad Firdaus
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  2. M. Akbar Rhamdhani
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  3. Yvonne Durandet
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  4. W. John Rankin
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  5. Kathie Mcgregor
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  6. Nathan A.S. Webster
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Corresponding author

Correspondence to Muhamad Firdaus .

Editor information

Editors and Affiliations

  1. Pennsylvania State University , University Park, Pennsylvania, USA

    Hojong Kim

  2. The University of Saskatchewan , Saskatoon, Saskatchewan, Canada

    Shafiq Alam

  3. IND LLC , South Jordan, Utah, USA

    Neale R. Neelameggham

  4. Umicore , Olen, Belgium

    Harald Oosterhof

  5. MIT , Cambridge, Massachusetts, USA

    Takanari Ouchi

  6. WATERTOWN, Massachusetts, USA

    Xiaofei Guan

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© 2017 The Minerals, Metals & Materials Society

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Firdaus, M., Akbar Rhamdhani, M., Durandet, Y., John Rankin, W., Mcgregor, K., Webster, N.A. (2017). Microstructure Observation of Oxidation of Nd-Magnet at High Temperatures. In: Kim, H., Alam, S., Neelameggham, N., Oosterhof, H., Ouchi, T., Guan, X. (eds) Rare Metal Technology 2017. The Minerals, Metals & Materials Series. Springer, Cham. https://doi.org/10.1007/978-3-319-51085-9_7

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