Dipolar energies in Nd-Fe-B nanocrystalline magnets with and without Nd-Cu infiltration

Abstract

We analyze the dipolar energies of Nd-Cu-infiltrated Nd-Fe-B nanocrystalline magnets during magnetization reversals by visualizing the magnetic dipolar interactions. Non-magnetic phases from the grains were identified by analyzing the element-specific magnetization distribution images taken with scanning transmission X-ray microscopy. The magnetic dipolar interactions were calculated from the interactions between the magnetization at each point and those at other points in the scanning transmission X-ray microscopy images. We present the dipolar energy distributions in Nd-Cu infiltrated nanocrystalline Nd-Fe-B magnets and compare them with those in nanocrystalline Nd-Fe-B magnets without Nd-Cu infiltration. The interplay between the exchange and dipolar interactions in Nd-Fe-B magnets is found to be essential for obtaining high coercivities. V

Relationship between magnetic nucleation and the microstructure of a hot-deformed permanent magnet: micromagnetic simulation

“…3e, and these fields are positive or almost zero inside the grains. In contrast, the dipole field has a nonuniform distribution 57,58 and a negative value in region A; the strength of the dipole field reaches 1.76 T in the z-direction. The total magnetic field approaches 4.56 T around region A, which exceeds the switching field of this grain.…”