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MURI-96 High Temperature Advanced Magnets
Final technical rept. 1 Sep 1996-31 Aug 2001
DELAWARE UNIV NEWARK
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A comprehensive and systematic study has been made on SmCOsub balFesub vCusub yZrsub xsub z magnets to completely understand the effects of composition and processing on their magnetic properties with the aim to increase their operating temperature. The homogenized SmCo, Fe, Cu, Zrsub z magnets have a featureless microstructure. A cellularlamellar 217R cells surrounded by 15 cell boundaries superimposed on 217H lamellar microstructure develops after 2-3 hours of aging at 800-850 deg C, but the coercivity increases only after a subsequent slow cooling to 400 deg C. During the cooling, diffusion takes place and Cu is concentrated in the 15 cell boundaries and Fe in the 217R cells. Our studies have led to compositions with operating temperatures above 400 deg C and with coercivities as high as 10 kOe at 500 deg Csup i. The high temperature performance of these magnets is very sensitive to the Cu content, which is believed to control both the coercivity and its temperature dependence. Furthermore, we developed a more economical heat treatment processing for higher Cu content magnets.
APPROVED FOR PUBLIC RELEASE