Title :
An investigation of domains and walls in two NdFeB alloys by transmission electron microscopy
Author :
Young, S. ; Chapman, J.N.
Author_Institution :
Dept. of Phys. & Astron., Glasgow Univ., UK
fDate :
11/1/1993 12:00:00 AM
Abstract :
Transmission electron microscopy (TEM) is used to investigate the domain structure in NdFeB alloys. The variation of domain period in thinned sections is studied for two different alloys, and an energy minimization model is used to calculate the specific domain wall energy (σ) for each alloy. For the basic alloy (A), a value for σ of 20.4 mJ/m2 is found, while the alloy with additions of Dy (B) has a value which is ~10% lower. This result is attributed to a decrease in the Re-TM exchange energy which more than offsets the increase in anisotropy resulting from the addition of Dy. The behavior of domains as they approach a grain boundary is investigated. It is observed that the relative orientation of the c-axes of two adjacent grains is extremely important in determining the behavior of the domain structure at the grain boundary
Keywords :
alloying additions; boron alloys; dysprosium alloys; exchange interactions (electron); ferromagnetic properties of substances; grain boundaries; iron alloys; magnetic anisotropy; magnetic domain walls; magnetic domains; neodymium alloys; permanent magnets; transmission electron microscope examination of materials; (TEM; NdFeB; NdFeBDy; Re-TM exchange energy; anisotropy; domain period; domain structure; domains; energy minimization model; grain boundary; specific domain wall energy; thinned sections; transmission electron microscopy; walls; Diffraction; Grain boundaries; Magnetic anisotropy; Magnetic domains; Magnetic field measurement; Magnetic materials; Magnetic properties; Micromagnetics; Perpendicular magnetic anisotropy; Transmission electron microscopy;
Journal_Title :
Magnetics, IEEE Transactions on
