Magnetic Microstructure of Sintered Nd-Fe-B Magnets Made from Casting Strips

The magnetic microstructures of two Dy-AI substituted sintered Nd-Fe-13 magnets with the different nominal compositions of Nd12.2Vy0.6Fe80.4Al0.7B6 (at.%) (composition-A,C-A) and Nd13.7Dy0.6Fe78.8Al0.7B6.2(at.%)(composition-B,C-13) prepared by strip casting technique have been revealed by using a magnetic force microscope. The magnetic properties of sintered C-B magnets are worse than that of C-A sintered magnets. In particular, the value of density products (BH)max for sintered C-A magnets is about 32% higher than that of C-B magnets, which is reflected by their quite different magnetic microstructures. We believe that for the C-B samples, the inappropriate composition and thus the redundant Nd2Fe17(B) phase of the casting strips make its final magnetic microstructures worse than the C-A, and then deteriorates the performance of the C-B magnets.