Interface and strengthening mechanisms of Al matrix composites reinforced with in-situ CNTs grown on Ti particles

The strengthening effect of carbon nanotubes (CNTs) in Al matrix composites (AMCs) is significantly weakened by CNTs agglomeration and unsubstantial interfacial bonding with the Al matrix. In this study, CNTs were grown on the surface of Ti particles by chemical vapor deposition to obtain CNTs@Ti hybrid reinforcement, followed by powder metallurgy to prepare CNTs@Ti/Al composites. Evenly dispersed CNTs with good structural integrity were successfully obtained using the carrying effect of the micron-sized Ti particles. Meanwhile, TiC, Al4C3, and TiAl3 were generated at the CNT/Al interface, which strengthened the bearing capacity of the inner-wall of the CNTs, improved the wettability of the CNT/Al interface, and enhanced the strain-hardening ability of the Al matrix. The deficiencies in the CNTs/Al composites are compensated by this kind of materials design, and the two types of reinforcements have a synergistic strengthening effect, which greatly improves the comprehensive mechanical properties of AMCs. An excellent interface structure is formed by controlling the interface reaction such that the dispersion, grain boundary, dislocation, and load transfer strengthening mechanisms are fully realized.