Effect of Sm-rich liquid phase on magnetic properties and microstructures of sintered 2:17-type Sm-Co magnet

The effect of Sm-rich liquid phase (Sm2Co3) on magnetic properties and microstructure of 2:17-type Sm-Co magnet was studied. Three phases existed in liquid phase ingot, and took on white, dark grey and grey, respectively. It was found that the composition of the grey area was similar to the nominal one. Our results indicated that the optimal composition was obtained at 3 wt.% liquid phase added, and the magnetic properties were Br=11.58 kGs, Hci >26 kOe, (BH)m=29.51 MGOe. Br increased by 3%, Hci was 13 times larger, and (BH)m was 6 times bigger than none liquid phase magnets. Moreover, with the aging time decreasing from 20 to 8 h, the squareness of the demagnetization curves got better, while the coercivity of the samples decreased. It revealed that Sm(Co, Cu)5 phase also precipitated at particle boundaries. It maybe also enhanced the coercivity.