Abstract
The growth process and microstructure of Au films electrodeposited on pure iron from KCN bath were examined by electronmicroscopy. The nuclei formed on (001) Fe at the early stage of electrodeposition were three-dimensional plate particles. With the progress of electrodeposition, these nuclei grew up into insular form and network in morphology, and finally into a complete continuous film, which is called “Au plate crystal” by the authors. The coherencies between Au plate crystal and iron substrate were (001) Fe||(001)Au and [110]Fe||[010]Au. In the growth process, a large number of dislocations, micro-twins and stacking faults were formed in the Au films. The density of dislocations was about 3-5×1010cm-2 and that of micro-twins was about 2×1010cm-2. The formation mechanism of micro-twins was identical with Burbank-Heidenreich's process or Hall-Thompson's process in evaporation. The length of twins was about 400-650Å. The sub-grains of less than 0.1μ in diameter were observed in the Au films of high indices formed on the substrate plane of high indices. The rotation Moire patterns existed in the vicinity of some of the sub-grain boundaries. Quantitative electronmicroscopic analysis of the Moire patterns and diffraction patterns revealed the growth of some of the crystals having orientations rotated and tilted at certain angles to the main plate crystal during their growing process.
