In this paper, nanocrystalline FeNi alloy powders with different particle size were prepared by two-step mechanical alloying (MA), the first step of the processes is FeNi nanocrystalline alloying and the second step modifies particle size. As-milled powders were randomly dispersed in paraffin at a weight ratio of 5:1 for microwave complex permeability test and comparision in the frequency range of 0.5-18 GHz. It is observed and discussed that microwave complex permeability is prominently affected by FeNi microstructure and particle size. In this work, Fe0.85Ni0.15 nanocrystalline powders exhibit high value of complex permeability in 1-10 GHz, and the sample with particle size of 2.34mm possesses the maximum value as m0 6.32 at 1.81GHz, m00 3.45 at 4.09 GHz. This value may be useful for thin-thickness and wide-band microwave absorber.

Z-type hexaferrite (Ba3(Co0.4Zn0.6)2Fe23.4O41) withBST(Ba 0.5Sr0.5TiO3) additive was prepared by conventional solidstate reaction method. We have investigated the effects of BST additive on the complex permeability, permittivity and microwave absorption in the range of 1 MHz-1 GHz. The results from XRD and SEM indicate that as the amount of BST increases, the major phase changes to Z-phase, simultaneously M-phase and perovskite phase appear, and grain size increases. When the weight percent of BST additive in Z-type hexaferrite varied from 0% to 1.5%, the BST additive not only improved complex permeability and complex permittivity, but also provided broadband reflectivity characteristics. Meanwhile the minimum reflection point shifts to lower frequency with increase of BST content.

The evolutions of microstructure of Fe0.85Ni0.15 products, which were prepared by mechanical alloying (MA) with and without process control agent (PCA), were studied using X-ray diffraction and scanning electron microscopy respectively. After MA without PCA (dry method) for 30h, Fe0.85Ni0.15 nanocrystalline alloy powders with bcc-Fe(Ni) phase were obtained; however, powders milled with PCA (wet method) from 20 to 90h, were unalloyed Fe-Ni mixtures with balanced morphology. It seems that dry method works efficiently in nanocrystalline alloying while wet method postpones MA but functionally fines the morphology of materials. Finally, the results were discussed considering the MA kinetics.

主要介绍了微波（GHz）频率下，高磁导率铁磁性薄膜近年来的最新研究进展。对于制备在柔性基片上的铁磁薄膜，重点介绍了Fe基、Co基合金薄膜，并分析了各成分对薄膜的影响；纳米晶薄膜的重点集中在Fe2N及FeXN系薄膜上，介绍了各类FeN相在薄膜中所起的作用；对于T2M2O系纳米磁性颗粒膜，分析了磁性颗粒膜的微波高磁导率机理。同时提出了目前探索GHz频率下高磁导率磁性薄膜主要面临的问题。

采用氧化物工艺制备Ba（Zn1-xCox）2Fe16O27六角铁氧体，通过不同含量Co2+、Cu2+对Zn2+的取代，发现平面型Ba（Zn1-xCox）2Fe16O27的μi-T曲线出现双峰（I、II）。随着Co2+、Cu2+含量的增加，第II峰分别移向高温和低温.并通过Ba（Zn1-xCox）2Fe16O27的磁晶各向异性常数Ku1、Ku2、Ku3随温度T的变化对实验结果进行了分析，所得结果对改善材料温度稳定性有实用价值。