The effects of intrinsic coercivity on the thermal stability of Sm(Co0.70Fe0.21Cu0.06Zr0.03)(7.6) sintered magnets up to 450 degrees

Sm(Co0.70Fe0.21Cu0.06Zr0.03)(7.6) sintered magnets with various H-ci have been prepared by the conventional powder metallurgy method. Five magnets with H-ci ranging from 15 to 40 kOe (at 25 degrees C) were selected to examine the impact of H-ci on the irreversible loss and reversible temperature coefficient of induction (cu). Magnets with higher H-ci and H-k were found to exhibit lower irreversible losses when heated to 450 degrees C. Unlike the irreversible loss, cr was found to be nearly independent of the H-ci or H-k. These trends suggest that the irreversible loss is microstructure related and can be manipulated by process control, while ct is more composition related and is dependent upon the overall chemical composition of the magnet. B-r of 8.3 kG, H-ci of 2.7 kOe, H,i of 3.5 kOe and BHmax of 6.7 MGOe at 450 degrees C were obtained on a Sm(Co0.70Fe0.21Cu0.06Zr0.03)(7.6) magnet with a H-ci of approximately 40 kOe at room temperature. Additional efforts are required to produce magnets which can be utilized at 450 degrees C. (C) 1997 American Institute of Physics.