Effect of ball-milling time on mechanical properties of carbon nanotubes reinforced aluminum matrix composites

Carbon nanotubes reinforced pure Al (CNT/Al) composites were produced by ball-milling and powder metallurgy. Microstructure and its evolution of the mixture powders and the fabricated composites were examined and the mechanical properties of the composites were tested. It was indicated that the CNTs were gradually dispersed into the Al matrix as ball-milling time increased and achieved a uniform dispersion after 6 h ball-milling. Further increasing the ball-milling time to 8–12 h resulted in serious damage to the CNTs. The tensile tests showed that as the ball-milling time increased, the tensile and yield strengths of the composites increased, while the elongation increased first and then decreased. The strengthening of CNTs increased significantly as the ball-milling time increased to 6 h, and then decreased when further increasing the ball-milling time. The yield strength of the composite with 6 h ball-milling increased by 42.3% compared with the matrix.