Effects of Cu Content on Microstructure and Compressive Properties of Carbon Nanotubes Reinforced Al-Cu Matrix Composite Foams

Appropriate addition of alloying elements is an effective way to enhance the mechanical properties of aluminum matrix composite foams. The powder metallurgy foaming method was used to prepare carbon nanotubes（CNTs）reinforced Al-Cu matrix（CNTs/Al-Cu） composite foams, and the effect of Cu content on the pore morphology,microstructure, quasi-static compressive mechanical properties, energy-absorption properties was investigated, as well as deformation modes. The fracture failure mechanism was analyzed by the compression fracture morphology. The results show that, with the increase of Cu content, the mechanical properties of the composite foams show a tendency to increase first and then decrease. The appropriate addition of Cu（3 wt%） can effectively optimize the pore morphology, promote the formation of fine grain zones and formation of intermetallic compounds at grain boundaries, thereby enhancing the compressive mechanical properties of the composite foams. Compared to Cu content of 2 wt%, the yield strength, plateau stress and energy absorption capacity increase by 18.0%, 33.0% and 39.5%, respectively. Additionally, the appropriate addition of Cu alters the compressive deformation mode of the composite foams and presents the combination of strengthening and toughening.