Unexpected Coercivity Enhancement &gt;1T for Nd-Fe-B Permanent Magnets With 20 wt% Nd Produced by Laser Powder Bed Fusion

Bittner, F.; Thielsch, Juliane; Drossel, Welf‐Guntram

doi:10.1109/tmag.2022.3167246

Cited by 7 publications

(1 citation statement)

References 24 publications

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“…[12][13][14][15] PBF-LB of commercial Nd-Fe-B magnet micropowders has already been studied in the literature, mainly focusing on laser processing parameters and their correlation to mechanical or magnetic properties. [16][17][18][19][20][21][22][23][24][25][26][27][28] It has been reported that direct energy deposition [29] or PBF-LB/M [21] of the commercially available Nd-Fe-B micropowder [30] (called MQP-S, see methods section for details) may cause the decrease or even absence of a hard magnetic phase. A recent study conducted by Tosoni et al [23] showed that the high cooling rates utilized in PBF-LB/M are advantageous for functional materials like Nd-Fe-B.…”

Section: Introductionmentioning

confidence: 99%

Influence of silver nanoparticle additivation on Nd-Fe-B permanent magnets produced by Laser Powder Bed Fusion

Gabriel

Liu

Staab

et al. 2023

Preprint

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Powder bed fusion of metals using a laser beam (PBF-LB/M) is an established additive manufacturing (AM) method that can be used to fabricate geometrically complex NdFe-B magnets. However, the magnetic properties of Nd-Fe-B magnets manufactured by PBF-LB/M are typically inferior to conventionally produced magnets. To overcome this drawback, we modified the surface of the permanent magnet feedstock powder with 1 wt.% surfactant-free Ag nanoparticles (NPs) supporting the formation of relevant phases required for permanent magnetic performance to achieve a suitable micro- and nanostructure after AM. Our study is accompanied by finite element simulations, revealing the impact and dependency of process parameters during PBF-LB/M: a wide temperature field with a high-gradient profile in the front and on the bottom of an overheated region, implying a vast local heating/cooling rate and in-process high thermal stress. We found experimentally that the as-built part density can be affected by both the laser power and scan speed, causing a reduction in density as both parameters increase. The functionality and microstructural properties are also investigated via VSM, HR-SEM, EDX, EBSD, and exemplarily with HR-TEM-EDX and APT. Our study found that modifying MQP-S with Ag NPs increases the coercivity by approximately 20%, which we correlate to a decreased grain size. Additionally, we identified three distinct phases in the modified and unmodified samples, where Ag is primarily found in the intergranular and Nd-rich phases of the as-built parts. Overall, the study's findings contribute to the understanding of the factors that affect the quality and magnetic properties of Nd-Fe-B magnets fabricated through PBF-LB/M and provide valuable insights for further research in this area.

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Section: Introductionmentioning

confidence: 99%

Influence of silver nanoparticle additivation on Nd-Fe-B permanent magnets produced by Laser Powder Bed Fusion

Gabriel

Liu

Staab

et al. 2023

Preprint

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Boosting Coercivity of 3D Printed Hard Magnets through Nano‐Modification of the Powder Feedstock

Gabriel,

Nallathambi,

Liu

et al. 2024

Advanced Science

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The demand for strong, compact permanent magnets essential for the energy transition drives innovation in magnet manufacturing. Additive manufacturing, particularly Powder Bed Fusion of metals using a laser beam (PBF‐LB/M), offers potential for near‐net‐shaped Nd‐Fe‐B permanent magnets but often falls short compared to conventional methods. A less explored strategy to enhance these magnets is feedstock modification with nanoparticles. It is demonstrated that modifying a Nd‐Fe‐B‐based feedstock with 1 wt.% Ag nanoparticles boost the coercivity of the magnets to a record value of 935 ± 6 kA m−1 without further post‐processing or heat treatments. Suitable volumetric energy densities for the PBF‐LB/M process are determined using finite element simulations predicting melt pool behavior and part density. Microstructural analyses reveal finer grain sizes and more equiaxed nanocrystalline structures due to the modification. Atom probe tomography identifies three phases in the Ag‐modified samples, with Ag forming nanophase regions with rare‐earth elements near the amorphous Zr‐Ti‐B‐rich intergranular phase, potentially decoupling the Nd2Fe14B primary phase. The study shows that superior magnetic properties primarily result from microstructure modification rather than part density. These findings highlight inventive material design approaches via feedstock surface modification to achieve superior magnetic performance in additively manufactured Nd‐Fe‐B magnets.

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A comparative study of Nd15Fe78B7 and Nd15Co78B7 systems: phase formations and coercivity mechanisms

Skokov

Schäfer

et al. 2022

Acta Materialia

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Unexpected Coercivity Enhancement >1T for Nd-Fe-B Permanent Magnets With 20 wt% Nd Produced by Laser Powder Bed Fusion

Cited by 7 publications

References 24 publications

Influence of silver nanoparticle additivation on Nd-Fe-B permanent magnets produced by Laser Powder Bed Fusion

Influence of silver nanoparticle additivation on Nd-Fe-B permanent magnets produced by Laser Powder Bed Fusion

Boosting Coercivity of 3D Printed Hard Magnets through Nano‐Modification of the Powder Feedstock

A comparative study of Nd15Fe78B7 and Nd15Co78B7 systems: phase formations and coercivity mechanisms

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