| Nanostructured (NS) metal materials is one of the most important part of nanotechnology. A quantitative of researches have been performed on mechanical properties of NS metal materials, involved synthesis and basic mechanical properties.Recently, electrodeposition has drawn more and more scientists'attention. The key of synthesizing NS metal materials is how to control the nucleation and growth of the crystals effectively. Compared to traditional electrodeposition, electrodeposition of NS metal materials has much larger current density, higher nucleation rate and lower crystal growth rate, so the grain size can be limited in the range of nanometers.Through a great deal of experiment and computer simulation, primary knowledge on plastic deformation mechanism of metal materials has been gained. It is admitted by most of the researchers that large size and quantities of samples is necessary for the accuracy of mechanical experiment. Due to the difficulties in synthesis of NS metal materials, small size even micro size samples are used in most of the mechanical experiments, at the same time, the sample shape always can not meet the need of stress state. Besides, the relationship between plastic deformation and strain rate has drawn more attention gradually. Some more important discoveries have been found in experiments.Some conclusions have been made as follows in this research:1. Influence of SeO2 as an additive on the surface morphology, microstructure and microhardness of electrodeposited NS Cu were investigated by XRD and SEM et al. According to the experiment, additive concentration at 0.02 g/L makes the surface of the electrodeposited coating smooth and compact, enhances the prior orientation (111) of the NS Cu, the grain size of the NS Cu decreased to 28 nm and the microhardness rises to HV277, which is about 5 times larger than that of the coarse-grained copper.2. Influence of current density on the electrodeposition rate, current efficiency , microstructure and microhardness of electrodeposited NS Cu were investigated by SEM, TEM and XRD et al. Results show that the electrodeposition rate increases remarkably and the current efficiency decreases while the current density increasing. Electrodeposited coating with a mirror surface and strong crystallographic texture on (111) can be obtained at a current density of 3.2 A/ dm2, which is porosity-free. At the same time, the average grain size of NS Cu decreases to 24 nm, and the microhardness increases to HV297, 5 times larger than that of the coarse-grained Cu.3. Effect of the electrolyte's pH value on electrodeposited NS Cu was also investigated. The results show that, the electrodeposition rate decreases with the increasing pH value,. When the PH value is 8.0, the electrodeposited NS Cu has crystallographic texture on (111) and the grain size goes beyond 100 nm. As the pH value ascends, prior orientation (220) of the NS Cu increases and the grain size decreases.4. Bulk NS Cu sheets with an average grain size of ~90 nm were fabricated by electrodeposition. In tensile tests at room temperature, compared with other NS Cu documented in the literature, this material exhibits a combination of high yield strength (356 MPa), good tensile elongation (18.2%) and ductile fracture features. The persistence of work hardening at large strains and strain rate sensitivity might be responsible for the enhanced ductility. 5. Microstructural analysis and tensile testing have been performed on a new nc Cu produced by pulse electrodeposition. The results show that the nc Cu, with an average grain size of 33 nm and a narrow grain size distribution, exhibits a high strength at the expense of a reduced ductility. By increasing the strain rate, the fracture strain decreases while the tensile stress increases noticeably. Strain hardening of the nc Cu sharply decreases after elastic deformation, which is responsible for the limited ductility. Analysis on fracture surfaces indicates a brittle feature at both high and low strain rate.
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