Effect of grain size on the electrical conductivity of copper-iron alloys

Copper-iron alloys (CFAs) are a much anticipated class of materials for electrical contacts, magnetic recordings, and sensors. In this study, Cu100-xFex alloys (x = 10, 30, or 50, representative of the Fe content in at%) were prepared via gas atomization, followed by sintering and heat treatment in vacuum. The electrical conductivity of the alloys was determined as a function of the grain size. The substitutional solid solution formed between copper and iron during alloy synthesis is decomposed during the subsequent heat treatment, followed by sluggish grain growth in samples of all compositions, but it was highest in the sample consisting of 10 at% of iron. In the samples with the other two compositions, grain growth was very slow and the grain boundaries were pinned by the Fe-rich phase. Bulk samples of all compositions with powder particles measuring ∼24 μm exhibited higher electrical conductivity with longer durations of heat treatment.