Title :
Stability of magnetic properties of Sm2Co17-type magnets at operating temperatures higher than 400°C
Author :
Handstein, A. ; Yan, A. ; Martinek, G. ; Gutfleisch, O. ; Müller, K.H. ; Schultz, L.
Author_Institution :
Leibniz Inst. of Solid State & Mater. Res., Dresden, Germany
Abstract :
The stability of the magnetic properties of Sm2Co17-type magnets at high operating temperatures was investigated by magnetic measurements at room temperature (RT) and high temperatures (HTs). The coercivity at RT is changed by the HT measurement and starts to decrease after measurements above 400°C. These changes in coercivity are attributed to microchemical changes in the bulk. The losses, however, can be fully recovered when the last segment of the original heat treatment of the magnet (550°C-400°C with 0.7K/min and 3 h at 400°C) was repeated. It was also found that prolonged exposure to air at high operating temperatures leads to a gradual decrease in remanence. Thus, coating the magnets is essential for the application of the magnets at high operating temperature in air.
Keywords :
cobalt alloys; coercive force; copper alloys; demagnetisation; ferromagnetic materials; heat treatment; iron alloys; permanent magnets; powder metallurgy; remanence; samarium alloys; sintering; zirconium alloys; 3 h; 400 to 550 C; Sm-Co-Fe-Cu-Zr; Sm2Co17-type magnets; coercivity; demagnetization curves; heat treatment; high operating temperatures; losses; magnet coating; magnetic measurements; magnetic properties stability; microchemical changes; prolonged air exposure; remanence; sintered magnets; Coercive force; Heat recovery; Heat treatment; Lead; Magnetic properties; Magnetic variables measurement; Magnets; Remanence; Stability; Temperature measurement;
Journal_Title :
Magnetics, IEEE Transactions on
DOI :
10.1109/TMAG.2003.815748