Microstructural analysis of copper clad steel (CCS) wires was performed after annealing using electron backscattered diffraction and a transmission electron microscope. Precipitation at the Cu/Fe interfaces was investigated, and the grain refinement mechanism was discussed. The results showed that elongated grains of copper and steel were gradually transformed into equiaxed grains after annealing. The grain sizes were increased with enhancing annealing temperature. The grains of copper and steel near the Cu/Fe interfaces showed a finer grain size distribution than those away from the interfaces. The microstructures of both copper and steel affected the deformation and re-crystallization of grains and sub-grains under the cladding state condition. The deformed grains were gradually transformed into re-crystallized grains and sub-grains with increasing annealing temperature. A number of precipitated Cu and α-Fe phases, ranging from 10 nm to 60 nm, were located near the Cu/Fe interfaces of CCS wires at the annealing temperature of 8°C. Based on a rigorous microstructural investigation, the grain refinement mechanism could be attributed to the appearance of sub-grains and precipitated phases at the Cu/Fe interfaces of CCS wires.

中文翻译：

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冷拔铜包钢线退火过程中晶粒细化的显微组织演变及机理

使用电子背散射衍射和透射电子显微镜对退火后的铜包钢 (CCS) 线进行微观结构分析。研究了 Cu/Fe 界面的沉淀，并讨论了晶粒细化机制。结果表明，铜和钢的拉长晶粒在退火后逐渐转变为等轴晶。晶粒尺寸随着退火温度的升高而增加。Cu/Fe界面附近的铜和钢晶粒比远离界面的晶粒尺寸分布更细。在熔覆状态下，铜和钢的显微组织均影响晶粒和亚晶粒的变形和再结晶。随着退火温度的升高，变形晶粒逐渐转变为再结晶晶粒和亚晶粒。在 8°C 的退火温度下，在 CCS 线的 Cu/Fe 界面附近有许多沉淀的 Cu 和 α-Fe 相，范围从 10 nm 到 60 nm。基于严格的微观结构研究，晶粒细化机制可归因于 CCS 线的 Cu/Fe 界面处亚晶粒和沉淀相的出现。