中文摘要：

以直流电弧等离子体法制备（Fe,Ni）的纳米粒子为前驱体,分别在350℃、400℃和450℃的氨气气氛中,通过热氨解反应合成（Fe,Ni）_4N包覆（Fe,Ni）纳米复合粒子。应用XRD,TEM,VSM,微波矢量网络分析仪对纳米粒子相成分、形貌、磁性和电磁参数进行了分析。结果表明,形成了（Fe,Ni）_4N包覆（Fe,Ni）纳米复合粒子。与前驱体粉体相比,纳米复合粒子的多重极化提高了复介电常数,且表现出明显的介电共振行为;而复磁导率呈现相似的变化规律,在8.0 GHz处出现了自然共振峰。利用电磁参数模拟微波吸收特性得出,氮化处理后复合粒子在3.6—7.8 GHz和2.0-6.4 GHz频率范围内具有良好的吸波性能（反射损耗R〈-10 dB）,最小反射损耗分别为-53.5 dB,-34.5 dB,可作为低频吸波剂。

英文摘要：

（Fe,Ni）_4N-coated（Fe,Ni） nanoparticles were synthesized by the thermal ammonolysis reaction in a NH_3 atmosphere at 400℃and 450℃using（Fe,Ni） nanoparticles as the precursor.The phase structure,composition,morphology,and the magnetic properties of the composite nanoparticles were examined by XRD,TEM and VSM.By dispersing the nanoparticles homogeneously into a paraffin matrix,the electromagnetic parameters of the nanoparticles were investigated in the frequency range of 2-18 GHz.The result show that the composite nanoparticles were（Fe,Ni） which were coated by（Fe, Ni）_4N.Compared to precursor nanoparticles,the composite particles after nitriding had a larger complex permittivity due to multi-dielectric polarization,while the complex permeability exhibited a similar change tendency and a natural resonance peak at 7.8 GHz.It is calculated that the excellent microwave absorption （R←10 dB）was obtained in the frequency range of 3.6-7.8 GHz and 2.0-6.4 GHz band,and that the minimum reflection loss were—53.5 dB and—34.5 dB at 3.2 GHz and 4.8 GHz for the composite particles at the nitriding temperatures of 400℃and 450℃,respectively.It may be used as a radar absorption material at low frequencies.