A novel strategy to design and fabricate Nd-Fe-B magnets

Highlights: • The demagnetization field distribution of a magnetized Nd-Fe-B magnet was calculated. • Composite Nd-Fe-B magnets with coercivity gradient distributions were fabricated. • The microstructure and chemical compositions near the bonding interface were studied. -- Abstract: The demagnetization field distribution of a magnetized Nd-Fe-B magnet was calculated and analyzed quantitatively. Multilayered composite Nd-Fe-B magnets with specific coercivity gradient distributions lower than the demagnetization field gradient were designed and fabricated via diffusion bonding under pressure. The magnetic property dependence on the interlayer magnet thickness was studied. The low coercivity interlayer magnet with the thickness lower than the critical value does not decrease the overall magnetic properties obviously. Effective self-bonding was observed in the interface between adjacent Nd-Fe-B magnets. The crystal orientations of matrix grains and the interface phase compositions were further studied. Multilayered composite Nd-Fe-B magnets make full use of the demagnetization field distribution to save the heavy rare earth Dy/Tb sources. This work paves a new way to design and fabricate Nd-Fe-B magnets with high magnetic properties.