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 h ave been prepared by the conventional powder metallurgy method. Five m agnets with H-ci ranging from 15 to 40 kOe (at 25 degrees C) were sele cted to examine the impact of H-ci on the irreversible loss and revers ible 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 ne arly independent of the H-ci or H-k. These trends suggest that the irr eversible loss is microstructure related and can be manipulated by pro cess control, while ct is more composition related and is dependent up on 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 wer e obtained on a Sm(Co0.70Fe0.21Cu0.06Zr0.03)(7.6) magnet with a H-ci o f approximately 40 kOe at room temperature. Additional efforts are req uired to produce magnets which can be utilized at 450 degrees C. (C) 1 997 American Institute of Physics.