Materials research for advanced inertial instrumentation; Task 3: Rare earth magnetic material technology as related to gyro torquers and motors

Preliminary measurements of flux decay rates of high coercivity and high energy product hot isostatically pressed (HIPed) SmCo5 magnets show that an increase of samarium content by one weight percent, increasing the Sm2Co7 second phase, raises the decay rate from minus 43 ppm/decade to minus 1070 ppm/decade. This finding may prove to be extremely valuable for producing high stability SmCo5 magnets. Oxygen contamination, determined to be the other major cause of instability, is expected to be significantly lowered with the use of the facilities being developed for fabrication of oxygen free SmCo5 magnets with the support of a related program.