Copper nanowires (CuNWs) with low manufacture price and high electrical conductivity have been successfully synthesized by a simple hydrothermal process. The molecular weight of amine, which was used as surfactant, largely influenced the morphology of synthesis Cu products. As-synthesized CuNWs were coated onto substrate and treated by intense pulse light (IPL) technique in ambient atmosphere. The instantaneous deoxidization and decomposition organics on the surface of the CuNWs contributed to the formation of transparent conductive film. A film with low sheet resistance of 13.4 Ω/□ and high transmittance of 79% was obtained. Furthermore, stretchable conductor was also realized by coating the CuNWs onto flexible substrate and following IPL sintering treatment.
The poor corrosion resistance of Mg alloys, which is well known as one of the lightest structural metal materials, limits a wide use of these alloys. In order to dramatically increase not only the corrosion resistance but also the surface hardness of Mg alloys (AZ80), coating with A2024 Al alloy by hot extrusion has been attempted in this study. The coating was successfully realized by hot extrusion of a Mg alloy (AZ80) billet together with an Al alloy plate placed between the billet and the extrusion die. The A2024 Al alloy-coated Mg alloy exhibited an excellent corrosion resistance and no weight loss was observed after immersion in a 5 mass% HCl aqueous solution for 10 min while a weight loss of about 1500 g・m-2 was observed in case of AZ80 Mg alloy without coating under the same condition. The surface hardness of the coated alloy was increased to about 85 HV by aging for 144 h at room temperature after solution treatment for 3 h at 673 K.
The recrystallized textures of 5083 aluminum alloy plates were examined. These plates were cold rolled at total reduction rates of 30, 50 and 85%, followed by annealing. When reduction rate was 30%, recrystallization was not complete and recovered grains remained despite annealing the specimen at 673 K for 10.8 ks in a salt bath. Recrystallized grains were mostly formed through particle stimulated nucleation, while strain induced grain boundary migration was scarcely occurred. The orientations of recrystallized grains were similar to those of the grains obtained after cold rolling. The orientations of recovered grains were returned to those of the grains before cold rolling with annealing. When reduction rate was 50%, the lattice rotations in the grains increased slightly as compared with the specimen that was cold rolled at a reduction rate of 30%. The distribution of the orientation was close to that of a β-fiber composed of copper, brass and S orientations. Several grains with the {142} plane parallel to the rolling direction were observed. On the contrary, the grains with the {111} plane parallel to the rolling direction decreased. When reduction rate was 85%, the image of the microstructure formed after cold rolling could not be obtained using SEM-EBSD. This was because Kikuchi patterns were not clear owing to the formation of dislocation tangles close to the rolling surface. EBSD images could be obtained by annealing the specimen at 673 K for 3 s. It can be considered that dislocation tangles were rearranged and changed into subgrains. The orientations of recrystallized grains close to precipitations were considerably irregular. However, these grains were difficult to grow. The grains with the {142} plane parallel to the rolling direction were more in the specimen cold rolled at a reduction rate of 85% than in the specimen cold rolled at a reduction rate of 50%. It was concluded that the <142>//ND texture was gradually constructed by increasing the total reduction rate for the cold rolling of 5083 aluminum alloy.
Formation of aluminum nitride (AlN) films on aluminum surfaces has been achieved by an electric discharge process in liquid nitrogen in very short time. The thickness of the film produced by this process ranged 10 and 20 μm for time varying between 0.12 and 1.2 ks. The film was composed of AlN and Aluminum-Oxynitride (AlON) and was found to have a complex structure. The film hardness ranged from 778 to 2333 HV, and was affected by the micro defects such as cracks and voids, and the presence of AlON in the film. The hardness was enriched by the presence of AlON.