INVESTIGATION OF THE COERCIVITY OF FE-SIO2 FINE PARTICLES ASSEMBLY PREPARED BY HIGH-ENERGY BALL-MILLING

Fe-SiO2 fine particle assembly, prepared by high-energy ball milling, exhibits coercivity which is enhanced by two orders of magnitude with respect to the alpha-iron. With increasing the fraction of x(v) from 0 .3 to 0.6, the coercivity of Fe-x(SiO2)(1-x) decreases from 350 Oe to 50 Oe. The coercivity of milled Fe-0.3(SiO2)(0.7) first increases, und ergoes a peak and then decreases, with increase in the deviation angle between the direction of external field and the aligned direction of the magnetically aligned powder-bonded samples. The magnetic reversal of Fe-SiO2 fine particles assembly can be explained by incoherent rota tion for small values of deviation angles, and by coherent rotation fo r large values of small deviation angles.