Long-term aging of Sm/sub 2/(Co,Fe,Cu,Zr)/sub 17/ permanent magnets at 300 and 400°C

Long-term aging experiments were carried out for Sm/sub 2/(Co,Fe,Cu,Zr)/sub 17/ permanent magnets at 300 and 400/spl deg/C and both traditional and application-oriented characterizations were performed. Results of application-oriented characterizations show that the maximum energy product of the magnet at 300/spl deg/C dropped /spl sim/10% after aging at 300/spl deg/C for 9200 hours. Further, the maximum energy product of the same magnet at 400/spl deg/C dropped /spl sim/43% after aging at 400/spl deg/C for 4300 hours. The findings also indicate that the thermal stability of Sm/sub 2/(Co,Fe,Cu,Zr)/sub 17/ magnets is extremely sensitive to their iron content in the magnet alloys. It is anticipated that the high temperature performance of Sm/sub 2/(Co,Fe,Cu,Zr)/sub 17/ magnets can be significantly improved by decreasing their iron content.