Hitoshi Nakae

Magnetic domain structures and domain walls in iron fine particles

In order to estimate the critical particle size lc for a single domain structure, the magnetic energy densities of an iron fine particle are calculated as a function of the particle size for various configurations of magnetization. It is assumed in this calculation that in a small particle the energy of a domain wall consists of the exchange, anisotropy, and magnetic stray field energies. It is found that lc is 20 nm for a particle with an axial ratio of n = 1, increases with an increase in n, and is 60 nm for a particle with n = 10. The wall energy of a fine particle is found to be much larger than that of bulk material owing to the stray field energy. Due to this wall energy, the magnetization configuration is the circular configuration of spins for the particle with a size larger than lc , and it becomes the flux closure configuration by four domains for the particle with a size larger than 900 nm if n = 1 and 600 nm if n = 10.

Cutting Texture of Fe-Si Alloy

The textures resulting from low speed cutting of Fe-3.14%Si alloy single crystals and polycrystalline specimens are examined by X-ray diffractometer. Some of results obtained are as follows.(1) Cutting the single crystals with various orientations, some preferred orientations were recognized in the deformed regions.(2) Cutting textures of polycrystalline specimens could be described as having {011} paral-lel to the cutting plane and parallel to the cutting direction. The dispersion of crystal orientation decreased with increasing grain size of those specimens. This {011} was characteristic component of textures in cutting surfaces, while it did not exsist in cold rolling textures of b. c. c. metals.(3) The main component {011} of the cutting textures of Fe-Si alloy was stronger in two pass cutting surface than one pass cutting surface.