Effect of z value on high temperature performance of Sm(Co,Fe,Cu,Zr)/sub z/ with z=7.14-8.10

The effect of z value on the high temperature performance of Sm(Co/sub 0.795/Fe/sub 0.09/Cu/sub 0.09/Zr/sub 0.025/)/sub z/ with effective z=7.14-8.10 was studied up to 600/spl deg/C. It was observed that the intrinsic coercivity (/sub M/H/sub c/) was very sensitive to the z value, especially when the temperature was lower than 550/spl deg/C. Peak values of /sub M/H/sub c/ were observed in the /sub M/H/sub c/-z curves. As the temperature rose, this peak shifted toward lower values of z. It was observed in this study that a new magnet with the composition of Sm(Co/sub 0.795/Fe/sub 0.09/Cu/sub 0.09/Zr/sub 0.025/)/sub 7.26/ showed maximum energy product more than 20 times higher than the best conventional high temperature 2:17 magnet in a dynamic characterization at 4000/spl deg/C. The new magnets with low z values and low Fe (high Co)content also displayed excellent long-term stability at 500/spl deg/C.