長時間鍛造した偏平状センダスト粉末・ポリマー複合体のマイクロ波帯透磁率

概要

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Fine flakes of Fe-Si-Al fabricated by forging for a long-duration exhibit a peculiar dual-peak dispersion in the frequency characteristics of the imaginary part of the permeability. This dual dispersion is composed of the dispersions D II and D III can be used to suppress noise in the quasi-microwave band. In a previous paper we clarified that the dispersion D II, which appears in the lower frequency range, is correlated to a shape anisotropy of the flakes. In this paper the origin of the dispersion D III is studied by analyses of crystalline structure changes during the forging (100 h to 180 h) and annealing processes. X-ray diffraction study and measurements of Moessbauer spectra strongly suggest that the annealed flakes have a two-phase structure consisting of an Fe-rich mother alloy and a Si/Al rich surface oxide layer. From the development of this structure accompanied by enhancement of the dual-peak profile of μ" as the forging time increases, it is concluded that the dispersion D III is caused by the magneto-elastic effect near the surface layer. High performance of conduction noise suppression in the microwave band for this composite was verified by setting them on a micro-strip line and measuring the transmission loss characteristics associated with the μ" dispersion D III.
社団法人日本磁気学会の論文
2002-06-01