Synthesis behavior of nanocrystalline Al-Al2O3 composite during low time mechanical milling process

;In this work, four different volume fractions of Al2O3(10, 20, 30 and 40 vol.%) were mixed with the fine Al powder and the powder blends were milled for 5 h. Scanning electron microscopy analysis, particle size analysis and bulk density measurements were used to investigate the morphological changes and achieving the steady state conditions. The results showed that increasing the Al2O3 content can provide the steady state particle size in 5 h milling process. It was found that increasing the volume fraction of Al2O3 leads to increasing the uniformity of Al2O3. Standard deviations of microhardness measurements confirmed this result. The XRD pattern and XRF investigations depicted that increasing the Al2O3 content causes an increase in the crystal defects, micro-strain and Fe contamination during 5 h milling process of nanocrystalline composite powders while the grain size is decreased. To investigate the effect of milling time, Al-30 vol.% Al2O3 (which achieved steady state during 5 h milling process) was milled for 1-4 h. The results depicted that the milling time lower than 5 h, do not achieve to steady state conditions. (C) 2011 Elsevier B.V. All rights reserved.