Structure and properties of nanocomposites prepared from ball milled 6061aluminium alloy with ZrO2 nanoparticles

Ball milling of 6061 aluminum alloy and nanocrystalline ZrO₂ powder allowed to obtain homogeneous mixture of nanocrystalline aluminum solid solution of grain size near 50 nm and ZrO₂ particles. The ZrO₂ particles are partially transformed after milling from tetragonal to the monoclinic crystal structure. After hot pressing in vacuum at temperature of 380 °C bulk nanocomposites were obtained of porosity below 1% consisting of aluminum solid solution of the average grain size near 80 nm and nano‐size ZrO₂ particles. Partial recrystallization occurred after hot pressing particularly near particles boundaries, where elongated recrystallized grains free from ZrO₂ nanoparticles of thickness near 1 μm and length of a few μm were identified. Estimated fraction of recrystallized grains was below 10%. The compression strength approaching 1000 MPa was obtained in composites containing 20% ZrO₂ nanoparticles, what is more than reported for ultra and nano‐grain 6XXX aluminum alloys. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)