Synergistic strengthening by load transfer mechanism and grain refinement of CNT/Al–Cu composites

CNT/Al–Cu composites were fabricated by mixing of Al powders and CNT/Cu composite powders which were prepared by molecular level mixing process. The CNT/Al–Cu–Cu composites show a microstructure with a homogeneous dispersion of CNTs in the Al–Cu matrix and had a 3.8 times increase of yield strength and 30% increase of elastic modulus compared to Al–Cu matrix. The strengthening mechanism of CNT/Al–Cu composites was discussed by controlling the aspect ratio of CNTs and it was thought that the CNT/Al–Cu composites were strengthened by both load transfer from the Al matrix to the CNTs and dispersion strengthening of damaged short CNTs. At the same time, the addition of CNTs increases the grain refinement effect of the Al–Cu matrix which results in a grain size strengthening mechanism of the CNT/Al–Cu composites.