The effect of Fe on the temperature dependent magnetic properties of Sm(Co,Fe,Cu,Zr)/sub z/ and SmCo/sub 5/ sintered magnets at 450/spl deg/C

The magnetic properties of SmCo/sub 5/, Sm(Co/sub bal/.Fe/sub 0.21/Cu/sub 0.06/Zr/sub 0.03/)/sub 7.6/, Sm(Co/sub bal/Fe/sub 0.25/Cu/sub 0.06/Zr/sub 0.03/)/sub 7.6/, Sm(Co/sub bal/Fe/sub 0.28/Cu/sub 0.06/Zr/sub 0.02/)/sub 7.6/, sintered magnets have been measured up to 350, 400 and 450/spl deg/C. For a fixed temperature range, the irreversible loss of Sm(Co,Fe,Cu,Zr)/sub z/ magnets has been found to increase with increasing Fe content, Despite the high B, obtained at 25/spl deg/C, a magnet must have a low irreversible loss of induction to retain a high magnetization after thermal cycling. Compromising the B/sub r/ of 11.3 kG obtained at 25/spl deg/C and the irreversible loss of 1.9% after thermal cycling to 450/spl deg/C, a magnet with the composition of the Sm(Co/sub bal/.Fe/sub 0.21/Cu/sub 0.6/Zr/sub 0.03/)/sub 7.6/ was found to exhibit the highest retained magnetization among the magnets studied. This magnet also exhibited the highest H/sub ci/ (2.8 kOe) and BH/sub max/ (6.7 MGOe) at 450/spl deg/C among all magnets studied. The reversible temperature coefficients of induction of Sm(Co,Fe,Cu,Zr)/sub 2/ sintered magnets were found to be about -0.03 to -0.04%//spl deg/C, while those of SmCo/sub 5/ magnet were about 0.05%//spl deg/C.