On the Effect of Current Density and Frequency of Pulse Electrodepostion on the Nanocrystalline Twins of Pure Copper

• Main Authors: Guang-Tai Liou, 劉光泰
• Other Authors: Jui-Chao Kuo
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/92593578177137438965

碩士 === 國立成功大學 === 材料科學及工程學系碩博士班 === 96 === In this study nano-twin coppers were synthesized by using a pulsed electrodeposition technique from an electrolyte of CuSO4, in which the current density and frequency were experiment parameters. Electron back-scattering diffractioin (EBSD) and XRD were carried on characterizing microstructure features of preferred orientation, grain size and boundary character. It was observed that the grain size decreases with increasing the current density and with decreasing the frequency. Increasing a current density leads to enhance a nucleation rate, resulting in a fine-grain microstructure. However, as a frequency increases, a disproportionation reation of cuprous ions and a dissolution reaction of copper adatoms into bulk solution, resulting in a coarse-grain microstructure. The average grain size of as-deposited coppers determined from XRD, EBSD and TEM are 82.9nm, 1.035μm and for 0.5μm to 1.0μm, respectively. The as-deposited Cu samples consisted of growth twins and irregular-shaped grains with a {110} preferred orientation. Scherrer’s equation is not able to determine a correct grain size of preferred orientation materials. The determination of grain size using XRD is limited due to the application of Scherrer’s equation. TEM images show a higher spatial resolution of microstructures than EBSD, but the observed area of EBSD could be several orders larger than that of TEM. This means that an orientation image map obtained from EBSD provides a higher accuracy in statistics than a microstructure from TEM.