LAUSR

Abstract Quasicrystalline aluminium alloys and aluminium based nanocomposites with the advantage of high strength over commercial aluminium alloys have been studied for many years. In this work a nanoquasicrystalline Al-Fe-Cr-Ti alloy powder and a nanocomposite consisting of a mixture of a nanoquasicrystalline alloy and nanosize γ-Al 2 O 3 powders were produced through mechanical milling with different milling speeds. It has been observed that a higher milling time or milling speed can improve the homogeneity of the γ-Al 2 O 3 distribution. The α-Al crystallite size decreases and the hardness increases with the milling time. The smallest crystallite size (14 nm) and the highest hardness value (638 HV 10g ) were obtained for the nanocomposite after 30 h of milling at 250 rpm. As the α-Al crystallite size is the main change in the microstructure during the ball milling process, the change in the hardness of the milled powders was found to follow a Hall-Petch type relation with an exponent of 0.25.