Study on Al-Si alloy-based nanocomposites with dispersed detonation nanodiamonds

Al-Si alloy-based nanocomposites with dispersed detonation nanodiamonds are fabricated by a powder metallurgy method. Rapid-solidified Al-Si alloy powder and detonation nanodiamond of 1% by volume are mechanically mixed at 500 rpm for 4 h; the nanoadditives used above are as-synthesized and purified detonation nanodiamonds. The obtained Al-Si nanocomposite mixtures are consolidated at 773 K by vacuum-hot pressing. The microstructural observations indicate that the fabricated Al-Si nanocomposites have fine grain structures with dispersed eutectic Si particles and detonation nanodiamonds in the grains; structural changes in the dispersed nanodiamonds are not observed. The mechanical and friction properties of the fabricated Al-Si nanocomposites with dispersed detonation nanodiamonds are investigated by carrying out indentation and friction measurements. It is observed that the dispersion of detonation nanodiamonds in the Al-Si alloy matrix improves its mechanical and friction properties. In particular, the dispersion of the purified detonation nanodiamond enhances the elastic modulus of the nanocomposite to a greater extent than that of the as-synthesized detonation nanodiamond with graphitic shell structure; in contrast, the use of the as-synthesized detonation nanodiamond reduces friction to a greater extent than the use of the purified detonation nanodiamond.