| The electronics information technique develops quickly nowadays. The electro-magnetism interference (EMI) becomes a severity problem. The Fe-Si-Al soft magnetic alloys, doesn't imply some strategic chemical elements such as Co, Ni, etc. It has the high permeability under the weak magnetic field, similar to Perm, but its saturation magnetization (Ms) and resistivity are larger, so it is more suitable for keeping in the high frequency usage. It was reported, that the composite magnetic material consisting of Fe-Si-Al flakes embedded in polymer, have excellent anti-EMI characteristic in the quasi-microwave segment.In this paper, the procedure of Fe-Si-Al flakes from melt-spun ribbons, with the composition of 9.7wt%Si- 5.6wt%Al-balFe, the ball mill skill and tempering influence to the microstructure and the electromagnetism of the samples, were investigated. It was found that the flaky morphology was remarkably improved by high planetary ball milling. The milling was performed in n-hexane with ball-to-power mass ratio of 5:1, and after ball milled for 70 hours, the ratio of plane to thickness can reach 10:1. The patterns of as-quenched Fe-Si-Al have super lattice peaks of the D03 structure. Then ball milled for some hours, the super lattice structure disappears, and only the bcc-Fe peaks are observed, while the grain size decreased and the internal strain increase. The evolutions of grain size and internal strain to milling time are fast firstly and then steady. The saturations magnetization Ms of the flakes can be effectively improved by annealing, and the coercivity was reduced. At the same time, the a-Fe structure of the ball-milled flakes re-returned to super structure of D03, when the annealing temperature was above 400℃. The average grain size of samples after annealed didn't grow unconventionally, and still kept in the range of nanometer. The toroidal samples made of the annealed flakes exhibits excellent anti-EMI characteristics at 1 GHz microwave range, because of the grain size and the saturations magnetization Ms of the annealed flakes increased. |
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