TriBeam tomography and microstructure evolution in additively manufactured Alnico magnets

Paul F. Rottmann; Andrew T. Polonsky; Toby Francis; Megan G. Emigh; Michael Krispin; Gotthard Rieger; McLean P. Echlin; Carlos G. Levi; Tresa M. Pollock

doi:10.1016/j.mattod.2021.05.003

TriBeam tomography and microstructure evolution in additively manufactured Alnico magnets

Paul F. Rottmann, Andrew T. Polonsky, Toby Francis, Megan G. Emigh, Michael Krispin, Gotthard Rieger, McLean P. Echlin, Carlos G. Levi, Tresa M. Pollock

Chemical and Materials Engineering

Research output: Contribution to journal › Article › peer-review

12 Scopus citations

Abstract

The Alnico 8 alloy has been printed using the selective laser melting additive manufacturing approach, resulting in material with magnetic properties in the as-printed state comparable to properties produced by conventional casting or powder metallurgy routes. Microstructural characterization in 3D, via electron backscattered diffraction (EBSD) in a TriBeam microscope, simultaneously reveals a fine-scale grain structure, grain orientations and sub-grain misorientation gradients as a function of proximity to spherical pores that form during the print process. The nanostructure of the 3D printed part has the same highly coherent spinodal α₁//α₂ structure observed in conventionally fabricated Alnico 8, which gives rise to a coercivity (H_c) of 51.2 kA m^-1. Further investigation of the phase constituents by TEM analysis provides an understanding of the microstructure evolution during the additive manufacturing process. Modified processing pathways for improved microstructure and properties are discussed.

Original language	English
Pages (from-to)	23-34
Number of pages	12
Journal	Materials Today
Volume	49
DOIs	https://doi.org/10.1016/j.mattod.2021.05.003
State	Published - Oct 2021

Bibliographical note

Funding Information:
This investigation was supported by Siemens Corporate Technology. The research reported here was also supported by the Materials Research Science and Engineering Center at UCSB (MRSEC NSF DMR 1720256) through IRG-1. Nanoval GmbH supplied the powder for SLM. The SLM buildup was performed by S.K. Rittinghaus from Fraunhofer Institute ILT. Powder EDS and EBSD were performed by A. Rucki () of Siemens CT. The authors also acknowledge Ram Seshadri from UC Santa Barbara for his useful discussions. The research made use of the MRL Shared Experimental Facilities, supported by the MRSEC Program of the NSF under Award No. DMR 1720256; a member of the NSF-funded Materials Research Facilities Network (www.mrfn.org).

Funding Information:
This investigation was supported by Siemens Corporate Technology. The research reported here was also supported by the Materials Research Science and Engineering Center at UCSB (MRSEC NSF DMR 1720256) through IRG-1. Nanoval GmbH supplied the powder for SLM. The SLM buildup was performed by S.K. Rittinghaus from Fraunhofer Institute ILT. Powder EDS and EBSD were performed by A. Rucki (?) of Siemens CT. The authors also acknowledge Ram Seshadri from UC Santa Barbara for his useful discussions. The research made use of the MRL Shared Experimental Facilities, supported by the MRSEC Program of the NSF under Award No. DMR 1720256; a member of the NSF-funded Materials Research Facilities Network (www.mrfn.org).

Publisher Copyright:
© 2021 Elsevier Ltd

Keywords

Additive manufacturing
Alnico
Selective laser melting
TEM
TriBeam

ASJC Scopus subject areas

Materials Science (all)
Condensed Matter Physics
Mechanics of Materials
Mechanical Engineering

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10.1016/j.mattod.2021.05.003

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title = "TriBeam tomography and microstructure evolution in additively manufactured Alnico magnets",

abstract = "The Alnico 8 alloy has been printed using the selective laser melting additive manufacturing approach, resulting in material with magnetic properties in the as-printed state comparable to properties produced by conventional casting or powder metallurgy routes. Microstructural characterization in 3D, via electron backscattered diffraction (EBSD) in a TriBeam microscope, simultaneously reveals a fine-scale grain structure, grain orientations and sub-grain misorientation gradients as a function of proximity to spherical pores that form during the print process. The nanostructure of the 3D printed part has the same highly coherent spinodal α1//α2 structure observed in conventionally fabricated Alnico 8, which gives rise to a coercivity (Hc) of 51.2 kA m-1. Further investigation of the phase constituents by TEM analysis provides an understanding of the microstructure evolution during the additive manufacturing process. Modified processing pathways for improved microstructure and properties are discussed.",

keywords = "Additive manufacturing, Alnico, Selective laser melting, TEM, TriBeam",

author = "Rottmann, {Paul F.} and Polonsky, {Andrew T.} and Toby Francis and Emigh, {Megan G.} and Michael Krispin and Gotthard Rieger and Echlin, {McLean P.} and Levi, {Carlos G.} and Pollock, {Tresa M.}",

note = "Funding Information: This investigation was supported by Siemens Corporate Technology. The research reported here was also supported by the Materials Research Science and Engineering Center at UCSB (MRSEC NSF DMR 1720256) through IRG-1. Nanoval GmbH supplied the powder for SLM. The SLM buildup was performed by S.K. Rittinghaus from Fraunhofer Institute ILT. Powder EDS and EBSD were performed by A. Rucki () of Siemens CT. The authors also acknowledge Ram Seshadri from UC Santa Barbara for his useful discussions. The research made use of the MRL Shared Experimental Facilities, supported by the MRSEC Program of the NSF under Award No. DMR 1720256; a member of the NSF-funded Materials Research Facilities Network (www.mrfn.org). Funding Information: This investigation was supported by Siemens Corporate Technology. The research reported here was also supported by the Materials Research Science and Engineering Center at UCSB (MRSEC NSF DMR 1720256) through IRG-1. Nanoval GmbH supplied the powder for SLM. The SLM buildup was performed by S.K. Rittinghaus from Fraunhofer Institute ILT. Powder EDS and EBSD were performed by A. Rucki (?) of Siemens CT. The authors also acknowledge Ram Seshadri from UC Santa Barbara for his useful discussions. The research made use of the MRL Shared Experimental Facilities, supported by the MRSEC Program of the NSF under Award No. DMR 1720256; a member of the NSF-funded Materials Research Facilities Network (www.mrfn.org). Publisher Copyright: {\textcopyright} 2021 Elsevier Ltd",

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doi = "10.1016/j.mattod.2021.05.003",

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AU - Polonsky, Andrew T.

AU - Francis, Toby

AU - Emigh, Megan G.

AU - Krispin, Michael

AU - Rieger, Gotthard

AU - Echlin, McLean P.

AU - Levi, Carlos G.

AU - Pollock, Tresa M.

N1 - Funding Information: This investigation was supported by Siemens Corporate Technology. The research reported here was also supported by the Materials Research Science and Engineering Center at UCSB (MRSEC NSF DMR 1720256) through IRG-1. Nanoval GmbH supplied the powder for SLM. The SLM buildup was performed by S.K. Rittinghaus from Fraunhofer Institute ILT. Powder EDS and EBSD were performed by A. Rucki () of Siemens CT. The authors also acknowledge Ram Seshadri from UC Santa Barbara for his useful discussions. The research made use of the MRL Shared Experimental Facilities, supported by the MRSEC Program of the NSF under Award No. DMR 1720256; a member of the NSF-funded Materials Research Facilities Network (www.mrfn.org). Funding Information: This investigation was supported by Siemens Corporate Technology. The research reported here was also supported by the Materials Research Science and Engineering Center at UCSB (MRSEC NSF DMR 1720256) through IRG-1. Nanoval GmbH supplied the powder for SLM. The SLM buildup was performed by S.K. Rittinghaus from Fraunhofer Institute ILT. Powder EDS and EBSD were performed by A. Rucki (?) of Siemens CT. The authors also acknowledge Ram Seshadri from UC Santa Barbara for his useful discussions. The research made use of the MRL Shared Experimental Facilities, supported by the MRSEC Program of the NSF under Award No. DMR 1720256; a member of the NSF-funded Materials Research Facilities Network (www.mrfn.org). Publisher Copyright: © 2021 Elsevier Ltd

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N2 - The Alnico 8 alloy has been printed using the selective laser melting additive manufacturing approach, resulting in material with magnetic properties in the as-printed state comparable to properties produced by conventional casting or powder metallurgy routes. Microstructural characterization in 3D, via electron backscattered diffraction (EBSD) in a TriBeam microscope, simultaneously reveals a fine-scale grain structure, grain orientations and sub-grain misorientation gradients as a function of proximity to spherical pores that form during the print process. The nanostructure of the 3D printed part has the same highly coherent spinodal α1//α2 structure observed in conventionally fabricated Alnico 8, which gives rise to a coercivity (Hc) of 51.2 kA m-1. Further investigation of the phase constituents by TEM analysis provides an understanding of the microstructure evolution during the additive manufacturing process. Modified processing pathways for improved microstructure and properties are discussed.

AB - The Alnico 8 alloy has been printed using the selective laser melting additive manufacturing approach, resulting in material with magnetic properties in the as-printed state comparable to properties produced by conventional casting or powder metallurgy routes. Microstructural characterization in 3D, via electron backscattered diffraction (EBSD) in a TriBeam microscope, simultaneously reveals a fine-scale grain structure, grain orientations and sub-grain misorientation gradients as a function of proximity to spherical pores that form during the print process. The nanostructure of the 3D printed part has the same highly coherent spinodal α1//α2 structure observed in conventionally fabricated Alnico 8, which gives rise to a coercivity (Hc) of 51.2 kA m-1. Further investigation of the phase constituents by TEM analysis provides an understanding of the microstructure evolution during the additive manufacturing process. Modified processing pathways for improved microstructure and properties are discussed.

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JO - Materials Today

JF - Materials Today

ER -

TriBeam tomography and microstructure evolution in additively manufactured Alnico magnets

Abstract

Bibliographical note

Keywords

ASJC Scopus subject areas

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