Laser powder bed fusion of NdFeB and influence of powder bed heating on density and magnetic properties
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jats:titleAbstract</jats:title>jats:pLaser powder bed fusion (L-PBF) is an additive manufacturing technique that provides an opportunity to create complex NdFeB magnets, potentially enhancing their performance. L-PBF possesses its own processing challenges, such as porosity/cracks and thermal stresses due to rapid cooling. This study focused on optimizing the parameters and the use of elevated temperature (300–550 °C) powder bed heating to reduce defect generation. This paper includes a detailed process parameter investigation, which revealed samples with a maximum energy product, jats:italic(BH)</jats:italic>jats:subjats:italicmax</jats:italic></jats:sub>, of 81 kJ/mjats:sup3</jats:sup> (remanence, jats:italicB</jats:italic>jats:subjats:italicr</jats:italic></jats:sub> 0.72 T; coercivity, jats:italicH</jats:italic>jats:subjats:italicci</jats:italic></jats:sub> 891 kA/m) without post/pretreatment, which are the highest jats:italic(BH)</jats:italic>jats:subjats:italicmax</jats:italic></jats:sub> and jats:italicB</jats:italic>jats:subjats:italicr</jats:italic></jats:sub> for L-PBF-processed NdFeB commercial powder. It was observed that all the high-magnetism samples possessed high density, but not all the high-density samples possessed high magnetism. The SEM images and discussions are academically valuable since they clearly illustrate grain formation and morphology in the melt pool, areas where the literature provides limited discussion. Furthermore, this paper incorporates quantitative phase analyses, revealing that the magnetic properties increase with increasing volume fraction of the strong magnetic phase Ndjats:sub2</jats:sub>Fejats:sub14</jats:sub>B. Another significant contribution of this paper is that it is the first study to investigate the effect of heated bed on L-PBF-NdFeB alloys. The density of the samples and jats:italicB</jats:italic>jats:subjats:italicr</jats:italic></jats:sub> can be improved with the use of elevated powder bed heating, while the jats:italicH</jats:italic>jats:subjats:italicc</jats:italic></jats:sub> decreases. The jats:italic(BH)</jats:italic>jats:subjats:italicmax</jats:italic></jats:sub> can also be improved from 55 to 84 kJ/mjats:sup3</jats:sup> through elevated powder bed heating. The maximum magnetic properties obtained with the heated bed (400 °C) were as follows: jats:italicB</jats:italic>jats:subjats:italicr</jats:italic></jats:sub>, 0.76 T; jats:italicH</jats:italic>jats:subjats:italicci</jats:italic></jats:sub>, 750 kA/m; and (jats:italicBH)</jats:italic>jats:subjats:italicmax</jats:italic></jats:sub>, 84 kJ/mjats:sup3</jats:sup>.</jats:p>
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Acknowledgements: The authors gratefully acknowledge Justin Mitchell and Doug Walston from Arnold Magnetic Technologies for Helmholtz coil tests /Magnetic Tests. The authors would like to thanks the EPSRC Future Manufacturing Hub in Manufacture using Advanced Powder Processes (MAPP) (EP/P006566/1) for their support during this investigation.
Funder: Republic of Türkiye Ministry of National Education
Funder: HiETA Technologies Limited
Funder: Equipmake
Funder: EPSRC Future Manufacturing Hub in Manufacture using Advanced Powder Processes (MAPP) (EP/ P006566/1)
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1433-3015