Fabrication of high-potential nanocomposite magnets by controlling crystallite orientation

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1. Fabrication of highly-oriented SmFe_<12>/alpha-Fe nanocomposite filmsWe have successfully fabricated a series of nanocomposite films composed of c-axis oriented SmFe_<12> (hard magnetic phase) and alpha-Fe (soft phase), and investigated the relation between the degree of orientation and magnetic properties. (1), sub/Ti/(SmFe_<12>, alphaFe)/Ti films : Although exchange-coupled nanocomposite films have been obtained over the entire range of alpha-Fe fraction VFe, the orientation of SmFe_<12> has been changed from (001)-texture to the mixture of (101) and (001) textures with increasing V_<Fe>. Both coercive force Hc and maximum energy product (BH)_<max> took a maximum around V_<Fe>=6%. (2), sub/(SmFe_<12>, alpha-Fe)/Ti films : By removing the Ti underlayers, we have for the first time succeeded to fabricate the highly-oriented SmFe_<12>/alpha-Fe nanocomposite films, in which(001)-texture has been kept up to V_<Fe>-50%. Both Hc and(BH)_<max> took a maximum around V_<fe> 25%, where (BH)_ … More <max> of 20 MGOe was obtained. (3), In order to analyze the origin of the magnetic properties, especially of the Hc increase, we have made a micromagnetic calculation and compared it with the experiment We then found that observed V_<Fe> dependence of H_c could be explained by using parameters of the weak exchange-coupling between hard phases and strong coupling between soft-hard phases.2. Fabrication of Nd-Fe-Co-B nanocomposite ribbons by high-field-annealingIn order to orient the easy axis of hard magnetic phase in bulk nanocomposite samples, we have investigated the effect of high-field annealing on the crystallization of amorphous ribbons, composed of Nd2(Fe_<1-x>Co_x)14B as a hard phase and (Fe_<1-x>Co_x) as a soft phase. It is found that, when the annealing temperature is below the Curie temperature of the hard phase, the volume fraction of the hard phase is larger in the field of 100 kOe than that in zero field. Any significant deviation from the random alignment has not been observed up to now Less