Shortened processing duration of high-performance Sm-Co-Fe-Cu-Zr magnets by stress-aging

Simultaneously achieving high energy product and high coercivity in the 2:17-type Sm-Co-Fe-Cu-Zr high temperature magnets has been closely relied on long-term isothermal aging to develop complete cellular nanostructure. In this work, we report a novel stress-aging approach that can substantially shorten the aging time to fabricate high-performance Sm-Co-Fe-Cu-Zr magnets. As exhibited by a model magnet Sm 25 Co 50.2 Fe 16. 2 Cu 5.6 Zr 3.0 (wt.%), applying 90 MPa compressive stress can shorten the aging time from 20 h for conventional isothermal aging to 10 h at the same aging temperature for achieving nearly equivalent magnetic performance. Further comparative study between the 10 h-aged samples under stresscontaining and stress-free conditions revealed that the stress not only promotes the precipitation of the cell boundary phase that are essential for enhancing the coercivity but also accelerates the dissociation of the cell edge defects that are detrimental to squareness factor, without destroying the [001] crystallographic texture. Such microstructural improvements enable the achievement of high-performance with maximum energy product of similar to 30 MGOe and coercivity above 35 kOe at reduced aging time. (c) 2022 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Automated summary

This study reports a novel stress-aging approach that can significantly shorten the aging time for fabricating high-performance Sm-Co-Fe-Cu-Zr magnets. Applying compressive stress promotes the precipitation of cell boundary phases and accelerates the dissociation of cell edge defects, resulting in high coercivity and high energy product.