Effect of coarse grain content on microstructure, cold workability and strain hardening behavior of trimodaled AA 6061 nanocomposites reinforced with multi-walled carbon nanotubes

•AA 6061-2 wt.% MWCNTs trimodal nanocomposites were fabricated by mechanical alloying.•Workability parameters of prepared trimodal nanocomposites were evaluated.•Strain hardening behavior of prepared trimodal nanocomposites was analyzed.

Trimodal nanocomposites of AA 6061 nanocrystalline (NC) matrix reinforced with 2 weight (wt.%) multi-walled carbon nanotubes (MWCNTs) blended with different wt.% (0, 5, 10, 15, 20 and 25) of coarse grain (CG) elemental powders related to AA 6061 alloy were successfully produced by 30 h of mechanical alloying (MA). MWCNTs were added at the end of 28th h of MA to avoid structural damage of MWCNTs. The study of improvement of compressive ductility while maintaining high strength and toughness for NC materials was carried out by incremental cold upsetting of bulk trimodaled composite. The 25% CG trimodal composite was observed to be the good one as it exhibited a better strain hardening behavior and high percentage of cold workability while maintaining considerable strength.

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