Texture analysis of ultra-high coercivity Sm₂Co₇ hot deformation magnets*

Abstract

Bulk anisotropic Sm2Co7 nanocrystalline magnets were successfully prepared by hot deformation process using spark plasma sintering technology. The coercivity of the isotropic Sm2Co7 nanocrystalline magnet is 34.76 kOe, further, the ultra-high coercivity of 50.68 kOe is obtained in the anisotropic hot deformed Sm2Co7 magnet when the height reduction is 70%, which is much higher than those of the ordinarily produced hot deformed Sm2Co7 magnet. X-ray diffraction (XRD) analysis shows that all the samples are Sm2Co7 single phase. The investigation by electron backscatter diffraction indicates that increasing the amount of deformation is beneficial to the improvement of the (00l) texture of Sm2Co7 magnets. The Sm2Co7 nanocrystalline magnet generates a strong c-axis crystallographic texture during large deformation process.

High and Ultra-High Coercive Materials in Spring-Exchange Systems—Review, Simulations and Perspective

“…The substitution of Fe by Co in many compounds and alloys leads to a remarkable increase in the Curie point. For example, well-known Sm-Co systems [ 16 , 17 , 18 , 19 ] such as SmCo 5 (hexagonal structure, P6/mmm), Sm 2 Co 7 (hexagonal structure, P6/mmc), and Sm 2 Co 17 (rhombohedral structure, P6/mmc) are important. The adequate crystal structures of these systems are presented in Figure 2 .…”

“…Generally, conventional (bulk and powder) Sm-Co compounds are good high-temperature permanent magnets, but they have a lower energy product | BH | max than Nd-Fe-B and a similar coercivity (not exceeding 1.2 T). Focusing on materials with ultra-high coercivity, the Sm 2 Co 7 compound was obtained by applying the so-called hot deformation, for which the coercive field reached the value of approximately 5 T [ 18 ].…”