Nanocrystalline Al–Al 2O 3p and SiC p composites produced by high-energy ball milling

Abstract

Composites based on the nanocrystalline aluminum alloy EN AW-2017 (3.9Cu, 0.6Mn, 0.7Mg, bal. Al, wt.%) and reinforced with 5 and 15 vol% SiC and Al 2O 3 particulates were successfully produced by high-energy ball milling process (HEM). The cellular structure of the CuAl 2 intermetallic phase initially present in the matrix and forming a net at the grain boundaries is fully destroyed and distributed along the deformation axis after 2 h milling. It was found that reinforcing matrix alloy with fine Al 2O 3 particles (−22 + 5 μm) slightly accelerates the milling process in contrast to using coarse SiC p (−55 + 25 μm). The results indicate that the particle size of the SiC p, Al 2O 3p and CuAl 2 was refined greatly after high-energy ball milling. However, it is clear that the reinforcing particle size distribution for both type of reinforcing particulates showed also a broad range of particle size even after the longest period of milling. Based on the X-ray line broadening analysis, namely the Williamson–Hall method, the crystallite size of the both type of composites was reduced to below 45 nm.