Effect of nanostructured Al on microstructure, microhardness and sliding wear behavior of Al–xGnP composites by powder metallurgy (PM) route

Abstract

AbstractIn the present work, Al-based metal matrix composites (MMCs) have been developed by the powder metallurgy (PM) route using exfoliated graphite nanoplatelets (xGnP) as nanofillers and their microstructure, microhardness and sliding wear behaviour were investigated. The Al-based MMCs were developed by using nanostructured Al powder developed by mechanical milling for 25 h in a high energy planetary ball mill. The crystallite size and lattice strain of Al after 25 h of milling were found to be 32 nm and 0.383 %, respectively. Al-1, 2, 3 wt.% xGnP composites were developed by the PM route. A significant improvement in both the microhardness and wear resistance of the Al–xGnP up to addition of 3 wt.% of the nanofiller was observed. For Al-3 wt.% xGnP composite developed using as-milled nanostructured Al, a microhardness of ∼ 1 GPa could be achieved, which is ∼6 times higher than that of the pure sintered Al sample (∼ 169.7 MPa). Nanostructured Al also leads to enhancement of the wear behaviour as compared to as-received Al. The wear mechanism in the various composites was found to involve a combination of abrasion, ploughing, delamination, microcracks, deep grooves and pullout of nanofillers.