Al–10% Al2O3-10% ZrO2 nanocomposite powders were fabricated by high-energy milling of the blended component powders. Planetary Monomill "Pulverisette 6" was used in milling the powders for 45 hours at 300 rpm and a ball-opowder ratio of 10:1. A uniform distribution of the Al2O3 and ZrO2 reinforcements in the Al matrix was ccessfully obtained after powders milling process. This uniform distribution was confirmed by characterizing these nanocomposite powders by scanning electron microscopy (SEM). X-ray diffraction (XRD) patterns were recorded for the milled powders, and analyzed using Williamson–Hall method to determine the crystallite size and the lattice strain. The crystallite size measurements were obtained using TEM observations in order to compare these results with those obtained from XRD