The syntheses of SiC p /Al nanocomposites under high pressure
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The syntheses of SiCpyAl nanocomposites under high pressure Haozhe Liu, Aimin Wang, Luhong Wang, Bingzhe Ding, and Zhuangqi Hu State Key Lab of RSA, Institute of Metal Research, Academia Sinica, Shenyang 110015, People’s Republic of China
Hongying Peng Lab of Atomic Imaging of Solids, Institute of Metal Research, Academia Sinica, Shenyang 110015, People’s Republic of China (Received 14 June 1996; accepted 19 November 1996)
The SiCpyAl nanocomposites were synthesized under high pressure. The reaction behavior between SiC particles and Al matrix within 2–6 GPa pressure range was determined. The high resolution electron microscopy (HREM) observation and the Vickers microhardness measurement show that the reaction is slight and that the adhesion of SiC particles to the Al matrix is good whether the reaction between them occurred or not. This offers an opportunity to tailor the nanocomposite mechanical properties by adjusting the synthesis temperature, pressure, and volume fraction of SiC particles.
The field of nanocomposites has recently attracted considerable attention, as researchers strive to enhance composites properties and extend their utilities by using nanoscale reinforcements instead of the more conventional particulate-filled composites.1 While smaller reinforcements have a better reinforcing effect than larger ones, they are also more difficult to handle, and have a larger surface-to-volume ratio, which means that they have a proportionately larger surface area over which chemical reactions and diffusion can occur. The development of composite materials made of an aluminum-base matrix reinforced with silicon carbide particles (SiCp ), whiskers (SiCw ), or fibers (SiCf ) has given grounds for substantial research on the physical and chemical phenomena during the fabrication or use of these materials.2–4 However, the thermodynamic principles governing the chemical interaction between the aluminum and nanoscale SiC particles during high pressure fabrication, which is used as a method to achieve a good bond between nanoscale SiC particles and the Al matrix and control reaction between them, were not systematically investigated. We report here the first SiCpyAl nanocomposites synthesized under high pressure, and well-bonded metal matrix nanocomposites were achieved. The microhardnesses of the nanocomposites, as a description of their mechanical properties, were tested. Aluminum powders (99.99% purity) and SiC powders, which were produced by laser-induced, vaporphase reactions and were about 30 nm in average particle diameter, uniformly distributed, and spherical in shape,5 were weighed according to contents of 5, 10, 20 vol % SiC, and ground for 5 h to distribute thoroughly the SiC powders. High pressure experiments were carried out in a belt-type apparatus.6 A temperature controller/programmer (Type 818) was used to control J. Mater. Res., Vol. 12, No. 5, May 1997
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