RE13Fe84Cr3(RE=Ce, Pr, Tb, Er) and Pr13-xFe84Cr3Tix(x=0, 2, 4, 6) alloy powders were prepared by arc smelting method and high energy ball milling technique. The phase structure and the morphology of the alloy powders were investigated by X-ray diffraction(XRD) and scanning electron microscopy(SEM), and their microwave absorbing properties were determined by a vector network analyzer. The results show that the alloys with light rare earths(Ce, Pr) have good low frequency absorbing property and those with heavy rare earths(Tb, Er) exhibit an improved high frequency absorbing property. The minimum refl ectivity at the absorbing peak frequency of RE13Fe84Cr3(RE=Ce, Pr, Tb, Er) are-9.49 d B at 5.76 GHz,-22.38 d B at 7.92 GHz,-18.52 d B at 11.68 GHz and-17.59 d B at 10.24 GHz, respectively. The absorbing bandwidth under-10 d B of the Pr13Fe84Cr3 powder was widened from 1.91 GHz to 3.89 GHz by adding 2% Ti, but the refl ectivity of the alloy was increased from-22.38 d B to-14.91 d B.
采用真空悬浮熔炼和高能球磨工艺制备Al8Mn5合金粉体,使用XRD和网络矢量分析仪研究回火温度对粉体组织结构和微波吸收特性的影响。结果表明:低于或等于400℃回火处理的高能球磨Al8Mn5合金粉体主要由Al8Mn5单相组成,600℃回火处理后,粉体主要由Al8Mn5、Al2Mn3和Mn2O3相组成;随回火温度升高,Al8Mn5粉体电磁参数虚部的共振频率、损耗因子的峰值频率和吸收峰频率均向高频方向移动;400℃回火粉体具有最强的吸波能力,涂层厚度为2.0 mm时,其反射率最小值达到-37 d B。
采用真空悬浮熔炼和高能球磨工艺制备(Al8Mn5)95Ni5微粉,并与石蜡按不同体积浓度制成复合材料,采用网络矢量分析仪研究(Al8Mn5)95Ni5微粉体积浓度对复合材料微波吸收特性的影响。结果表明:随着(Al8Mn5)95Ni5微粉体积浓度的增加,复合材料的ε″共振峰频率、μ″共振峰频率和反射损耗峰频率均向低频方向移动;涂层厚度为1.5 mm时,(Al8Mn5)95Ni5微粉体积浓度为30%的复合材料具有最小的反射损耗峰值(约为-34.98 d B)和很好的频宽效果;增加复合材料中(Al8Mn5)95Ni5微粉体积浓度,被吸波涂层表面反射回去的电磁波会增多。
采用高能球磨和热处理工艺制备了MnAl合金粉体,使用SEM、XRD和网络矢量分析仪研究Al含量对MnAl合金粉体组织结构和微波吸收特性的影响。结果表明:随Al含量的增加,MnAl合金粉体中Al0.89Mn1.11、β-Mn和Al2Mn3含量降低、Al8Mn5含量升高,使粉体磁损耗和介电损耗增加、共振频率向低频移动、吸收峰数增加。吸波层厚度为2.0mm时,Mn40Al60样品在12.2 GHz频率处有最大吸收峰,其反射率最小值为–26.5 d B,具有较好的频宽效果。MnAl粉体对电磁波的吸波机理包括吸波涂层内的损耗以及前后界面反射电磁波在前界面处的干涉损耗。
采用真空悬浮熔炼和高能球磨工艺制备Mn-Al基合金粉体,使用XRD、SEM和网络矢量分析仪研究Ce含量对MnAl粉体组织结构和微波吸收特性的影响。结果表明:随着加入Ce含量的增加,AlMnCe粉体Al_8Mn_4Ce相随着增多,同时AlMnCe合金粉体复数介电常数虚部ε″和复数磁导率虚部μ″的共振峰频率及反射损耗峰频率均向低频移动;当涂层厚度为1.8 mm时,Al_8Mn_4Ce粉体的反射率最小值达到约–26.9 d B。
