Development of dy-free NdFeB anisotropic bonded magnet (New MAGFINE)

The authors have successfully developed a low-cost anisotropic NdFeB magnet powder with high coercivity value of 18kOe without any Dy additives by diffusion processing of Nd-Cu-Al element to anisotropic magnet powder produced by the d-HDDR method. This enhancement mechanism is to isolate the magnetic couple between grain of Nd₂Fe₁₄B phase by creation of non-magnetic grain boundaries of Nd and Cu. By surface coating on this anisotropic magnet powder, the long-term aging loss behavior under air at 150deg.C has been improved by 6% after 1,000hr compared to current MAGFINE material without powder surface coating. By using this new anisotropic bonded magnet (New-MAGFINE), small automotive motors with excellent thermal stability and low cost characteristics have become possible.