Abstract:The Y-Fe-Cr alloy powders were prepared by the arc melting method and high energy ball milling, then the powders prepared were sealed in evacuated quartz tubes for homogenization annealing at 1 123 K for 2 h. The phase structure and the microstructure of the alloys powders were analyzed by X-ray diffractometry and scanning electron microscopy, then their microwave absorbing properties were analyzed by vector network analyzer. And the effect of heat treatment on the powders by sample Y₁₁Fe₈₆Cr₃ was studied. The results show that the Y_xFe_97−xCr₃ (x=7, 9, 11, 13, mole fraction, %) alloys powders have better wide-frequency characteristic under 1.5 mm of material thickness. At low frequency, the microwave absorbing properties of the Y₉Fe₈₈Cr₃ alloy are better than those of the others. The reflectivity of Y₇Fe₉₀Cr₃ , Y₁₁Fe₈₆Cr₃ or Y₁₃Fe₈₄Cr₃ is lower than −6 dB at microwave ranging from 7 GHz to 18 GHz. The reflectivity obviously increases after heat treatment under 1.8 mm of material thickness; near the absorption peak, the least reflectivity turns from −10.5 dB to −13.8 dB, and the wide frequency of reflectivity under −10 dB achieves 5 GHz. Nevertheless, the heat treatment can not increase but decrease the microwave absorbing property except the region near the least reflectivity peak.

Key words: Y-Fe-Cr alloy; microwave absorber; arc melting method; high energy ball milling