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. 2023 Jun 21;13(13):1899.
doi: 10.3390/nano13131899.

Hard Magnetic Properties and the Features of Nanostructure of High-Temperature Sm-Co-Fe-Cu-Zr Magnet with Abnormal Temperature Dependence of Coercivity

O A Golovnia  1   2 , A G Popov  1 , N V Mushnikov  1 , A V Protasov  1   2 , K G Pradeep  3 , A V Ogurtsov  4 , D V Taranov  4 , A M Tishin  5
Affiliations

Hard Magnetic Properties and the Features of Nanostructure of High-Temperature Sm-Co-Fe-Cu-Zr Magnet with Abnormal Temperature Dependence of Coercivity

O A Golovnia et al. Nanomaterials (Basel). .

Abstract

This paper presents methods and approaches that can be used for production of Sm-Co-Fe-Cu-Zr permanent magnets with working temperatures of up to 550 °C. It is shown that the content of Sm, Cu, and Fe significantly affects the coercivity (Hc) value at high operating temperatures. A decrease in the content of Fe, which replaces Co, and an increase in the content of Sm in Sm-Co-Fe-Cu-Zr alloys lead to a decrease in Hc value at room temperature, but significantly increase Hc at temperatures of about 500 °C. Increasing the Cu concentration enhances the Hc values at all operating temperatures. From analysis of the dependence of temperature coefficients of the coercivity on the concentrations of various constituent elements in this alloy, the optimum chemical composition that qualifies for high-temperature permanent magnet (HTPM) application were determined. 3D atom probe tomography analysis shows that the nanostructure of the HTPM is characterized by the formation of Sm2(Co,Fe)17 (2:17) cells relatively smaller in size along with the slightly thickened Sm(Co,Cu)5 (1:5) boundary phase compared to those of the high-energy permanent magnet compositions. An inhomogeneous distribution of Cu was also noticed in the 1:5 phase. At the boundary between 1:5 and 2:17 phases, an interface with lowered anisotropy constants has developed, which could be the reason for the observed high coercivity values.

Keywords: Sm2Co17; SmCo5; nanocrystalline cellular structure; permanent magnets.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Temperature dependencies of coercivity of the Sm(Co0.978−yCuyZr0.022)7.3 magnets, data from [17].
Figure 2
Figure 2
Temperature dependencies of the coercivity of the Sm(Co0.978−x−yFexCuyZr0.022)7.3 magnets, data from [17,36].
Figure 3
Figure 3
Dependence of temperature coefficients of coercivity β on Cu content in (1) the Sm(Co0.978−yCuyZr0.022)7.3 and (2) Sm(Co0.88−yFe0.1CuyZr0.02)7 magnets.
Figure 4
Figure 4
(a) Temperature dependencies of coercivity of Sm(Co0.88−xFexCu0.09Zr0.03)7; (b) demagnetization curves of magnets with x = 0.
Figure 5
Figure 5
Dependence of temperature coefficients of coercivity β on Fe content in magnets: (1) Sm(Co0.88−xFexCu0.09Zr0.03)7; (2) Sm(Co0.92−xFexCu0.06Zr0.02)7.6; (3) Sm(Co0.89−xFexCu0.078Zr0.03)8.3.
Figure 6
Figure 6
Dependence of the temperature coefficient of coercivity β on Sm content of the (1) Sm(Co0.753Fe0.14Cu0.08Zr0.027)z and (2) Sm(Co0.795Fe0.09Cu0.09Zr0.025)z magnets.
Figure 7
Figure 7
Dependence of the temperature coefficient of coercivity β on the Zr content of the Sm(Co0.82−vFe0.09Cu0.09Zrv)7.2 magnets.
Figure 8
Figure 8
(a) Cu and Zr; (b) Cu; (c) Zr overlaid with the respective isoconcentration surfaces of 7 at.% Cu and 10 at.% Zr.
Figure 9
Figure 9
(a) Elemental distribution map of Cu with a 7 at.% isoconcentration surface (b); proxigram obtained from a representative Cu-rich region (marked with a rectangle in (a)) with a 0.1 nm bin width.
Figure 10
Figure 10
(a) Localization of the element distributions obtained using a 10-nm diameter cylindrical region of interest. (b) Element distributions and (c) anisotropy constant calculation K1.
See this image and copyright information in PMC

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