Nanocrystalline diamond films have been successfully synthesized on plastic substrates at substrate temperatures below 100°C using a microwave plasma chemical-vapor deposition technique. This has been realized by using low reaction-gas pressures and a surface-wave plasma with a low-electron temperature over the growth region. The nanocrystalline diamond films exhibit growth rates with much lower temperature dependence than conventional diamond growth and decreasing nucleation rates with increasing substrate temperatures. These phenomena imply a different growth mechanism from conventional diamond syntheses. In addition, our analysis on the crystal size distribution of the nanocrystalline diamond film indicates the possibility of diamond nucleation in a stable phase in the plasma. The gas-phase nucleation, invoked by the low-electron temperature of the surface-wave plasma, well explains the low-temperature growth and the temperature dependences of the growth rate and the nucleation rate.

Bismuth, a non-magnetic material with a crystal magnetic anisotropy was vaporized by laser and resistance heating methods and deposited on a glass plate as a substrate in a high magnetic field of 12 T. The glass plate was set at the position with the maximum magnetic field intensity in perpendicular to the magnetic field direction. In the case of the laser heating method, the tendency of crystalline orientation in a thin film obtained in the presence of the high magnetic field did not agree with the theoretical prediction derived from the viewpoint of magnetization energy, and the particles on the film surface became coarser. On the other hand, in the case of the resistance heating method, the tendency of crystalline orientation appeared as expected from the theoretical prediction and a finer particle size was obtained in the presence of the magnetic field. Furthermore, a new evaluation method for crystalline orientation has been proposed.

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ABSTRACTWe have examined tensile properties of a novel heat-resistant aluminium (Al)-based alloy (with a composition of Al-5Mg-3.5Zn (at%)) strengthened by the T-Al6Mg11Zn11 (cubic) intermetallic phase at various temperatures. The tested specimens of the present alloy were solution-treated at 450°C for 24 h and subsequently aged at 200 or 300 oC for 1 h. The granular precipitates of the T phase were dispersed rather homogenously in the grain interior in the specimen aged at 300°C. In the specimen aged at 200°C, numerous fine precipitates with a mean size of ∼20 nm were observed in the α-Al matrix. The specimen pre-aged at 200°C for 1 h exhibited a superior strength to the conventional Al alloys at elevated temperatures ranging from 150 to 200°C (corresponding to service temperatures for compressor impellers in turbochargers).

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