Load transfer strengthening in carbon nanotubes reinforced metal matrix composites via in-situ tensile tests

In-situ observation of tensile tests were performed to investigate the strengthening mechanisms of multi-walled carbon nanotube (MWCNT) reinforced Al matrix composites (AMCs). Carbon nanotubes (CNTs) were effectively incorporated and aligned in AMCs through a conventional powder metallurgy route. During tensile failure, the fracture process of CNTs in fabricated AMCs was clearly observed, suggesting the effective load transfer between the matrix and CNTs, and between inner walls of MWCNTs. Due to the small reinforcing effect of other factors, load transfer strengthening dominantly contributed to the observed high strengthening efficiency in CNT/Al composite, agreeing with the predicted results of the shear-lag model. This study provided evidence supporting the theory behind load transfer strengthening mechanisms of CNTs in metal matrix composites.