The influence of Tb substitution on the magnetic properties of nanocomposite Pr2Fe14B/alpha-Fe magnets

Tb-doped (Pr,Tb)(2)Fe14B/alpha -Fe nanocomposite ribbons have been synthesi zed by melt-spinning Pr8-xTbxFe86B6 alloys at low speeds. The effects of Tb substitution and rapid annealing on the magnetic properties of the composi tes were investigated. With a small addition of Tb, the Curie temperature o f hard phase increases slightly, the saturation magnetization decreases but the coercivity increases due to a higher anisotropy field and a refinement of grain size, leading to an enhancement in the energy product. Transmissi on electron microscopy revealed a finer and more homogeneous (PrTb)(2)Fe14B /alpha -Femicrostructure with an average grain size in the range from 20 to 40 nm. The best results are obtained with a room temperature coercivity of 6.6 kOe, M-r = 118 emu/g, and (BH)(m) = 15.2 MGOe in Pr7Tb1Fe86B6, sample annealed at 800 degreesC for 1 minute.