The structure and processes of mass, charge and heat transfer are investigated in an equiatomic Fe–Ni composite fabricated by electroconsolidation using the spark plasma sintering (SPS) technology. The system contains regions of almost pure Fe and Ni, separated by areas with variable concentration of components, formed in consequence of the interdiffusion in the electroconsolidation process. The interdiffusion coefficient of the Fe–Ni system has been revealed to be significantly higher than that of an alloy of a similar composition at the same temperature, which is likely the result of the employed SPS technology and the enhanced diffusion along the grain boundaries. The concentration dependence of the interdiffusion coefficient passes through a maximum at a Ni concentration of ∼70 at.%. The electrical and thermal conductivity of the studied system is significantly higher than that of an alloy of the same composition. The temperature dependence of the resistivity of the sample in the range 5–300 K is due to the scattering of electrons by defects and phonons, and the scattering of electrons by phonons fits well to the Bloch–Grüneisen–Wilson relation. The boundaries of the conductivity of the investigated composite correspond to the Hashin–Shtrikman boundaries for a three-phase system, if Fe, Ni and the FeNi alloy are selected as phases.

中文翻译：

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电固结 FeNi 复合材料中传输过程的结构诱导特征

在使用放电等离子烧结 (SPS) 技术通过电固结制备的等原子 Fe-Ni 复合材料中研究了质量、电荷和传热的结构和过程。该系统包含几乎纯铁和镍的区域，由不同浓度的组分区域隔开，这是由于电固结过程中的相互扩散而形成的。Fe-Ni 系统的相互扩散系数显着高于相同温度下类似成分的合金，这可能是采用 SPS 技术和增强沿晶界扩散的结果。相互扩散系数的浓度依赖性在 Ni 浓度为～70 at.%。所研究系统的电导率和热导率明显高于相同成分的合金。样品电阻率在 5-300 K 范围内的温度依赖性是由于缺陷和声子对电子的散射，而声子对电子的散射非常符合 Bloch-Grüneisen-Wilson 关系。如果选择 Fe、Ni 和 FeNi 合金作为相，所研究的复合材料的电导率边界对应于三相系统的 Hashin-Shtrikman 边界。