(Fe,Co)2(P,Si) rare-earth free permanent magnets: From macroscopic single crystals to submicron-sized particles

H. Yibole, B. Lingling-Bao, J. Y. Xu, H. Alata, O. Tegus, W. Hanggai, N. H. van Dijk, E. Brück, F. Guillou*

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

Abstract

While rare-earth magnets exhibit unchallenged hard-magnetic properties, looking for alternatives based on inexpensive elements of non-critical supply remains of utmost interest. Here, we demonstrate that (Fe,Co)2(P,Si) single crystals combine a large magnetocrystalline anisotropy (K1 ≈ 0.9 MJ m−3 at 300 K), high Curie temperatures (TC up to 560 K) and an appreciable saturation specific magnetization (101 A m2 kg−1) leading to a theoretical |BH|max ≈ 165 kJ m-3, making them promising candidate materials as rare-earth-free permanent magnets. Our comparison between (Fe,Co)2P and (Fe,Co)2(P,Si) single crystals highlights that Si substitution reduces the low-temperature magnetocrystalline anisotropy, but strongly enhances TC, making the latter quaternary alloys most favorable for room temperature applications. Submicron-sized particles of Fe1.75Co0.20P0.75Si0.25 were prepared by a top-down ball-milling approach. While the energy products of bonded particles are to this point modest, they demonstrate that permanent magnetic properties can be achieved in (Fe,Co)2(P,Si) quaternary alloys. This work correlates the development of permanent magnetic properties to a control of the microstructure. It paves the way toward the realization of permanent magnetic properties in (Fe,Co)2(P,Si) alloys made of economically competitive Fe, P and Si elements, making these materials desirable for applications.

Original languageEnglish
Article number117388
Number of pages9
JournalActa Materialia
Volume221
DOIs
Publication statusPublished - 2021

Keywords

  • Magnetic properties
  • Magnetism
  • Nanomaterials
  • Single crystal

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