THE EFFECT OF HfB₂ ON MAGNETIC PROPERTIES OF NANOCOMPOSITE Fe₂Nd₁₄B / Fe₃B MAGNET

By adding lwt.% HfB₂ into Nd_(3-4)Fe_(77-78.5)B_(18.5) alloys, the grain growth of Fe₃B/Nd₂Fe₁₄B composite phases during annealing was found to be hindered by 40~50%. It is proposed that the addition of HfB₂ leads to the formation of fine dispersoids of HfB₂ in the Fe₃B/Nd₂Fe₁₄B composite magnet. The maximum energy product((B.H)max) as well as intrinsic coercivity(iHc) for the Nd₃Fe_(78.5)B_(18.5)+lwt.% HfB₂ alloy were enhanced by more than 25% (B.H)max=10 MGOe, iHc=2.5 kOe) due to the addition of HfB₂ while remanent magntization(Br) was reduced slightly. It is deduced that the formation of fine dispersoids will also play a role of magnetic domain pinning.