Single-crystallization of electrolytic copper foils

Depending on the production process, copper (Cu) foils can be classified into two types, i.e., rolled copper (r-Cu) foils and electrolytic copper (e-Cu) foils. Owing to their high electrical conductivity and ductility at low cost, e-Cu foils are employed extensively in modern industries and account for more than 98% of the Cu foil market share. However, industrial e-Cu foils have never been single-crystallized due to their high density of grain boundaries, various grain orientations and vast impurities originating from the electrochemical deposition process. Here, we report a methodology of transforming industrial e-Cu foils into single crystals by facet copy from a single-crystal template. Different facets of both low and high indices are successfully produced, and the thickness of the single crystal can reach 500 mu m. Crystallographic characterizations directly recognized the single-crystal copy process, confirming the complete assimilation impact from the template. The obtained single-crystal e-Cu foils exhibit remarkably improved ductility (elongation-to-fracture of 105% vs . 25%), fatigue performance (the average numbers of cycles to failure of 160 0 vs . 20 0) and electrical property (electrical conductivity of 102.6% of the international annealed copper standard (IACS) vs . 98.5%) than original ones. This work opens up a new avenue for the preparation of single-crystal e-Cu foils and may expand their applications in high-speed, flexible, and wearable devices. (c) 2023 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.