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Title: Microstructural and magnetic property evolution with different heat-treatment conditions in an alnico alloy

Abstract

Further property enhancement of alnico, an attractive near-term, non-rare-earth permanent magnet alloy system, primarily composed of Al, Ni, Co, and Fe, relies on improved morphology control and size refinement of its complex spinodally decomposed nanostructure that forms during heat-treatment. Using a combination of transmission electron microscopy and atom probe tomography techniques, this study evaluates the magnetic properties and microstructures of an isotropic 32.4Fe-38.1Co-12.9Ni-7.3Al-6.4Ti-3.0Cu (wt.%) alloy in terms of processing parameters such as annealing temperature, annealing time, application of an external magnetic field, as well as low-temperature “draw” annealing. Optimal spinodal morphology and spacing is formed within a narrow temperature and time range (~840 °C and 10 min) during thermal-magnetic annealing (MA). The ideal morphology is a mosaic structure consisting of periodically arrayed ~40 nm diameter (Fe-Co)-rich rods (α1 phase) embedded in an (Al-Ni)-rich (α2 phase) matrix. A Cu-enriched phase with a size of ~3–5 nm is located at the corners of two adjacent {110} facets of the α1 phase. The MA process significantly increased remanence (Br) (~40–70%) of the alloy due to biased elongation of the α1α1 phase along the <100> crystallographic direction, which is closest in orientation to the applied magnetic field. Here, the optimum magnetic properties of themore » alloy with an intrinsic coercivity (Hcj) of 1845 Oe and a maximum energy product (BHmax) of 5.9 MGOe were attributed to the uniformity of the mosaic structure.« less

Authors:
 [1];  [1];  [1];  [2];  [2];  [1];  [1]
  1. Ames Lab., Ames, IA (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Ames Lab., Ames, IA (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1361376
Alternate Identifier(s):
OSTI ID: 1363632; OSTI ID: 1417110
Report Number(s):
IS-J-9288
Journal ID: ISSN 1359-6454; KC0403040; ERKCZ01
Grant/Contract Number:  
AC05-00OR22725; AC02-07CH11358
Resource Type:
Accepted Manuscript
Journal Name:
Acta Materialia
Additional Journal Information:
Journal Volume: 133; Journal Issue: C; Journal ID: ISSN 1359-6454
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; permanent magnet; alnico; spinodal decomposition; transmission electron microscopy

Citation Formats

Zhou, Lin, Tang, Wei, Ke, Liqin, Guo, Wei, Poplawsky, Jonathan D., Anderson, Iver E., and Kramer, Matthew J. Microstructural and magnetic property evolution with different heat-treatment conditions in an alnico alloy. United States: N. p., 2017. Web. https://doi.org/10.1016/j.actamat.2017.05.012.
Zhou, Lin, Tang, Wei, Ke, Liqin, Guo, Wei, Poplawsky, Jonathan D., Anderson, Iver E., & Kramer, Matthew J. Microstructural and magnetic property evolution with different heat-treatment conditions in an alnico alloy. United States. https://doi.org/10.1016/j.actamat.2017.05.012
Zhou, Lin, Tang, Wei, Ke, Liqin, Guo, Wei, Poplawsky, Jonathan D., Anderson, Iver E., and Kramer, Matthew J. Mon . "Microstructural and magnetic property evolution with different heat-treatment conditions in an alnico alloy". United States. https://doi.org/10.1016/j.actamat.2017.05.012. https://www.osti.gov/servlets/purl/1361376.
@article{osti_1361376,
title = {Microstructural and magnetic property evolution with different heat-treatment conditions in an alnico alloy},
author = {Zhou, Lin and Tang, Wei and Ke, Liqin and Guo, Wei and Poplawsky, Jonathan D. and Anderson, Iver E. and Kramer, Matthew J.},
abstractNote = {Further property enhancement of alnico, an attractive near-term, non-rare-earth permanent magnet alloy system, primarily composed of Al, Ni, Co, and Fe, relies on improved morphology control and size refinement of its complex spinodally decomposed nanostructure that forms during heat-treatment. Using a combination of transmission electron microscopy and atom probe tomography techniques, this study evaluates the magnetic properties and microstructures of an isotropic 32.4Fe-38.1Co-12.9Ni-7.3Al-6.4Ti-3.0Cu (wt.%) alloy in terms of processing parameters such as annealing temperature, annealing time, application of an external magnetic field, as well as low-temperature “draw” annealing. Optimal spinodal morphology and spacing is formed within a narrow temperature and time range (~840 °C and 10 min) during thermal-magnetic annealing (MA). The ideal morphology is a mosaic structure consisting of periodically arrayed ~40 nm diameter (Fe-Co)-rich rods (α1 phase) embedded in an (Al-Ni)-rich (α2 phase) matrix. A Cu-enriched phase with a size of ~3–5 nm is located at the corners of two adjacent {110} facets of the α1 phase. The MA process significantly increased remanence (Br) (~40–70%) of the alloy due to biased elongation of the α1α1 phase along the <100> crystallographic direction, which is closest in orientation to the applied magnetic field. Here, the optimum magnetic properties of the alloy with an intrinsic coercivity (Hcj) of 1845 Oe and a maximum energy product (BHmax) of 5.9 MGOe were attributed to the uniformity of the mosaic structure.},
doi = {10.1016/j.actamat.2017.05.012},
journal = {Acta Materialia},
number = C,
volume = 133,
place = {United States},
year = {2017},
month = {5}
}

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Cited by: 11 works
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Works referenced in this record:

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    Works referencing / citing this record:

    Processing of Alnico Magnets by Additive Manufacturing
    journal, November 2019

    • White, Emma; Rinko, Emily; Prost, Timothy
    • Applied Sciences, Vol. 9, Issue 22
    • DOI: 10.3390/app9224843

    The corrosion mechanism of the sintered (Ce, Nd)-Fe-B magnets prepared by double main phase and single main phase approaches
    journal, May 2018

    • Shi, Xiaoning; Zhu, Minggang; Zhou, Dong
    • AIP Advances, Vol. 8, Issue 5
    • DOI: 10.1063/1.5007316