Microstructure and damping properties of ultra fine grained Al wires reinforced by Al2O3 nanoparticles

Commercial purity Al and A1 based composite wires reinforced with alumina nanoparticles were produced via powder metallurgy route. Powder of Al and Al with 2 wt.% of nano-Al2O3 particles were processed by high-energy ball milling. The powders were consolidated by hot extrusion into billets and then rolled to wires down to a square section of 1 mm2. Commercially pure Al and Al- 2wt.% Al2O3 powders were successfully consolidated by hot extrusion at 400°C and cold rolled down to wires of 1 mm2 in section without failures. The ball milling process led to the fragmentation of the native oxide layer that covers the Al powders into nano-sized particles and favored the embedding of these phases in the Al matrix. Then, also commercially pure Al wires took advantage of the strengthening effect of the hard particles. The nanocomposite exhibited higher hardness (about 10%) and higher internal friction than the Al sample.