MAGNETIC NANOCOMPOSITES BY REACTION MILLING

Systems of small magnetic particles embedded in a nonmagnetic matrix w ere prepared by high energy ball milling. Besides carefully chosen mil ling conditions, in situ chemical reactions were used to control the p roperties of the product. Nanocomposites of iron particles in metal ox ides (Al2O3 and ZnO), and magnetite particles in copper metal were pre pared by reaction milling. The samples were characterized by X-ray dif fraction and magnetic methods. A few hours of ball milling resulted in the completion of most chemical changes. Iron nanoparticles were form ed with lattice strains of about 0.005; coercivities up to 400 Oe were achieved The magnetization of the iron particles is 25-40% less than that expected for bulk iron.