The use of cryogenic milling to prepare high performance Al2009 matrix composites with dispersive carbon nanotubes

Al2009 matrix composites reinforced with highly dispersive carbon nanotubes (CNTs) were prepared by cryogenic milling combined with powder metallurgy, the structure evolution of CNTs during preparation and the mechanical properties of composites were investigated. The results show that short CNTs with uniform distribution were obtained in aluminum powders through cryomilling. Most CNTs retained tubular structure in composites except only minimal ones reacted with aluminum and formed Al4C3. The dispersity of CNTs in composites gradually decreased with rising addition, and limited dispersion was found when CNTs content reached at 1.5wt.%. The ultimate tensile and yield strength of 1.0wt.% CNTs/2009 composite at natural aged condition were 560MPa and 443.3MPa respectively, which enhanced 25% and 24% compared to Al2009 aluminum alloy prepared by the same process. Moreover, it still showed good ductility with elongation of 10.2%. The cryogenic milling is promising to prepare homogeneously distributed carbon nanotubes reinforced composites with high performance. [Display omitted] •Cryogenic milling can shorten CNTs with less time.•CNT distributed highly homogeneously in Al2009 powder and the composites.•CNTs had minimal damage and most of them retained tubular structure.•Interface bonding enhanced by CNT partially reacted with Al.•1.0 wt.% CNT/2009-T4 composite exhibited high strength and ductility.