Abstract
The isothermal aging–microstructure–magnetic property relationship of a SmCo 2:17 alloy was investigated in the present study. The alloy also contained Fe, Cu and Zr as major addition. Its magnetic properties, including intrinsic coecivity Hci, remanence Br and maximum energy product (BH)max, were obtained from the measured second quadrant M–H hysteresis curves. The microstructure of the alloy was characterised using X-ray diffraction (XRD) and TEM. It was found that, as the one step aging temperature was increased from 850 to 900°C, the remanence of the SmCo 2:17 alloy magnet was increased while its coercivity was reduced. The maximum energy product (HB)max of the magnet was significantly improved by applying a two step aging, consisting of aging first at 900°C followed by aging at 850°C. Based on XRD and TEM analyses, effects of the aging condition on the microstructure and magnetic properties were discussed. The microstructural change observed in the current work included cell size of the cellular structure and the degree of Cu segregation at the cell boundaries. Change in the degree of Cu segregation at the cell boundaries might be the major cause for the change in coercivity of the alloy aged in different aging conditions. The effect of aging condition on the remanence could be attributed to the effect of aging condition on cell size of the cellular structure, which affects the volume fraction of SmCo 2:17 phase in the alloy.