Microstructure and mechanical properties of fly ash particle reinforced AA6061 composites produced by press and extrusion

AA6061-fly ash particle composites were fabricated using cold pressing followed by hot extrusion. Composites containing 2, 6 and 10 wt.% fly ash particles were fabricated. Matrix alloy samples without fly ash content were also prepared for comparison. Optical microscopy, Xray diffractrometry, Scanning Electron Microscopy and Transmission Electron Microscopy were adopted for characterizing the composites. Uniform distribution of fly ash particles was observed in composites. Hardness and tensile strength of the 2 wt.% fly ash composite were found to be better compared to the monolithic alloy after age-hardening. However, further increase of fly ash content resulted in poor age-hardening due to the depletion of Mg from the alloy matrix and transfer to the fly ash interface, which was confirmed by EDX analysis.