Sytrthesis And Mechanical Properties Of Bulk Nanocrystalline Copper By Electrical Brush-plating Technique

In mechanical testing of materials, sufficient amount of specimens with larger size isaccepted publicly as the prerequisite to get the experimental results correctly. However,due to the difficulty of preparing nano large metal materials, nano-mechanical propertiesof the metal current tests are usually using a small sample size and even micro size.Meanwhile, the sample are often unable to meet the conditions of stress, the materialproperties of the thus obtained test results of often untrusted. There is an urgent need tosolve the problem is how to prepare a larger blocks and metal materials with nanometerreal nanostructures. In order to solve the problems mentioned above, this paper made thefollowing experimental work, and gives the corresponding research results:1. Experimental methods to improve traditional electric brush plating, using this newmethod preparation of the brush-plated nanocrystalline copper (nc-Cu), and parsethe brush-plated nc-Cu deposition process of the reaction mechanism and growthmechanism. Anode is absorbent cotton and pp fabric package of stainless steel. Thecomposition of the plating solution are CuSO4·5H2O, NH4NO3and trace amounts ofadditives. The use of additives in solution can reduce the grain size of sediments,inhibit the formation of bulky grain variety, etc. Reasonably control dc voltage,temperature of the plating solution and the speed of plating pen can preparation ofhigh quality block nc-Cu sample.2. Using X-ray diffraction, scanning electron microscopy spectrometer, field emissionelectron microscopy and transmission electron microscopy on a comprehensiveanalysis of the characterization of the brush-plated nc-Cu. We can know from theanalysis of test results: the experiment of brush plating nanometer copper grain structure is equiaxed grain structure, the grain size distribution is more uniform, inthe crystal didn’t find the existence of the micro defects such as cracks, pores. Thesurface of Brush plating nanometer copper is smooth and the surface roughness islow, and have good smoothness and coverage. Results show that by improving thepreparation method of brush plating, the block nanometer copper is a real sense ofnanocrystalline materials.3. Using the electro-hydraulic servo testing machine and nano indentation apparatus ofbrush plating nanometer copper at room temperature tensile experiments and nanoindentation experiment under different depth. Room temperature tensile experimentresults show that the tensile strength of nc-Cu brush plating presents gradually in-crease when the tensile strain rate increased from10-4s-1to1s-1. In terms of plastic,the elongation decreases with the increase of tensile strain rate. Brush plating na-nometer copper under different strain rate are ductile fracture, the fracture surface isuneven at low strain rate, the fracture surface appears obvious haircuts under highstrain rate. Hardness value is obtained by nano indentation experiment calculation ofnanometer copper brush plating, strain rate sensitivity of m value presents obvioustwo paragraphs, and m values present increases gradually with the increase of in-dentation depth of the trend. Through the analysis of the brush plating nanometercopper deformation mechanism, that we learned that the deformation of the brushplating nanometer copper in this experiment is by the grain boundary and disloca-tion mechanism to work together, but there are some differents under high strain rateand low strain rate and deformation mechanism. The deformation of the brush plat-ing nanometer copper predominantly dislocation activity under high strain rate, butat low strain rate,the deformation is grain boundary sliding mechanism and a smallamount of thermal activation of grain boundary diffusion.