電解液溫度對直流電解沉積納米孿晶Cu微觀結(jié)構(gòu)的影響

電解液溫度對直流電解沉積納米孿晶Cu微觀結(jié)構(gòu)的影響Effect of Electrolyte Temperature on Microstructures of Direct-Current Electrodeposited Nanotwinned Cu

本研究通過控制直流電解沉積電解液溫度制備出不同微觀結(jié)構(gòu)的塊體納米孿晶Cu樣品。結(jié)果表明當(dāng)電解液溫度由313 K降低至293 K，納米孿晶Cu的平均晶粒尺寸由27.6 μm減小至2.8 μm，平均孿晶片層厚度由111 nm減小至28 nm。電化學(xué)測試表明降低溫度減緩了納米孿晶Cu沉積的電化學(xué)過程，使陰極過電位增大，引起了晶粒和孿晶的形核率增加，從而使晶粒尺寸和孿晶片層厚度同時減小。

Recent studies indicate that nanotwinned (nt) metals can simultaneously possess high strength, good ductility, outstanding fatigue resistance and considerable electrical conductivity. These superior properties are strongly dependent on their structures i.e. the twin length (grain size), the twin thickness and the twin orientation. Understanding the synthesis process and its relation to the resulting microstructure is key to fabricate and optimize the nt metals. In this work, by means of direct-current electrodeposition, we studied the effect of the electrolyte temperature on microstructures of nt-Cu samples. Microstructure characterizations indicated that as-deposited nt-Cu samples were composed of micro-sized columnar grains with nanoscale twins parallel to the growth surface at different electrolyte temperatures. Both the grain size and the twin thickness decreased when the deposition temperature decreased from 313 K to 293 K. Electrochemical tests suggested that with decreasing the electrolyte temperature, the equilibrium potential, exchange and diffusion-limited current densities of the working electrode decreased, which resulted in an elevated overpotential. As a consequence, both the nucleation rates of grains and twins were enhanced, which resulted in a decrease in the grain size and the twin thickness.

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