Study On Heat Treatment Of High Coercivity 2:17 Type SmCo Permanent Magnets

High coercivity 2:17 type SmCo permanent magnets have a irreplaceable statue in high temperature magnets field. In order to have a better understanding on heat treatment processN magnetic properties and microstructure, the components of high coercivhy 2:17 type SmCo permanent magnets were designed, lots of experiments and theoretic analysis have been carried out by use of modern analysis means including optical microscopy > scanning electron microscopy (SEM) ^ x-ray diffraction analysis (XRD) and energy dispersive analysis (EDA).The effects of sintering process on microstructure and magnetic properties of Sm2(CoCuFeZr)n magnets had been investigated. The results of experiments showed that the gas absorbed on the surface of powder grains has been gave out during presintering in vacuum. The best properties of the material presintered at 1190癈 for 30 minutes has been obtained. The pore of the samples decreased obviously, and the density and increased after sintered in an argon atmosphere. Magnets sintered at 1210 癈 for 60 minutes had the best magnetic properties, iheBr of 1.0IT (lO.lkGs), Hclof 1655.7kA/m (20.8kOe) and (fl#)换 of 184.7kJ/m3 (23.2MGOe).The aim of solid solution treatment was to co-solute the melted two phases completely, and form excessive saturated solid solution, then prepare for forming cellular microstructure at aging treatment. The magnets had the best properties solid solution treated at 1180C for 120 minutes.The effects of aging process on micro structure and magnetic properties of Sni2(CoCuFeZr)i7 magnets had been studied. The results of the experiments showed that aging treatments had no influence on sample's density and remanence, but had great influence on intrinsic coercivity and magnetic energy products. At 10 hours one-step isothermal aging treatment, the intrinsic coercivhy and magnetic energy products were the highest at 800 "C and enhanced with the increasing of temperature between 400C and 800 C, then overaging took place at 900C which causing the decreasing of intrinsic coercivity and magnetic energy products. The cellular microstructure could be formed in short time during one-step isothermal aging at the temperature of 830 C, but intrinsic coercivity and magnetic energy products were low. As the aging times reaching 10 hours, intrinsic coercivity and magnetic energy products increased greatly. The cellular microstructure was decomposed in part, afterlong time (30 hours) aging, both of the intrinsic coercivity and magnetic energy products decreased greatly. The more the steps of multiple-steps aging, the higher the intrinsic coercivity and magnetic energy products. The process of temperature controlled cooling two-steps aging had the same effect as multiple-steps aging. The slower the rate of temperature controlled cooling, the higher the magnetic properties.At last, a kind of applicable process of heat treatment was obtained. The magnetic properties of the sample approached to the international advanced level, Br of 1.075T(10.75kGs), Hci of 2098.2kA/m (26.36kOe), Hcb of 776.1 kA/m (9.75kOe), HK of843.8kA/m(10.60kOe)and (BH)m of 210kJ/m3 (26.38MGOe).