Annealing temperature effect on microstructure, magnetic and microwave properties of Fe-based amorphous alloy powders

摘要

Fe_(74)Ni_3Si_(130Cr_6W_4 amorphous alloy powders were annealed at different temperature (T) for 1.5 h to fabricate the corresponding amorphous and nanocrystalline powders. The influences of T on the crystalline structure, morphology, magnetic and microwave electromagnetic properties of the resultant samples were investigated via X-ray diffraction, scanning electron microscopy, vibrating sample magnetometer and vector network analyzer. The results show that the powder samples obtained at T of 650 ℃ or more are composed of lots of ultra-fine oc-Fe(Si) grains embedded in an amorphous matrix. When T increases from 350 to 750 ℃, the saturated magnetization and coercivity of the as-annealed powder samples both increase monotonously whereas the relative real permittivity shows a minimal value and the relative real permeability shows a maximal value at T of 650 ℃. Thus the powder samples annealed at 650 ℃ show optimal reflection loss under -10 dB in the whole C-band. These results here suggest that the annealing heat treatment of Fe-based amorphous alloy is an effective approach to fabricate high performance microwave absorber with reasonable permittivity and large permeability simultaneously via adjusting T.