Improvement of interfacial interaction and mechanical properties in aluminum matrix composites reinforced with Cu-coated carbon nanotubes

Controlling the interfacial interaction is a prerequisite for the preparation of aluminum matrix composites reinforced by carbon nanotubes (CNTs) with high performance. In this paper, Cu-coated CNTs fabricated by the compound reduction method were applied to control the interfacial interaction between carbon nanotubes and aluminum matrix for improving the interfacial bonding and mechanical properties of aluminum matrix com-posites. The microstructure, interfacial structure, interfacial interaction, and mechanical properties of Cu-coated composite were studied in detail. The in-depth study results show that Cu nanoparticles act as a bridge con-necting the carbon nanotubes and matrix and forming Al2Cu intermetallic, which is in favour for better dispersion of carbon nanotubes and interfacial bonding. In addition, Cu nanoparticles are preferentially deposited at the defects of carbon nanotubes to repair the defects and inhibit the formation of brittle Al4C3 phases. As a result, Cu-coated composite displays the superior strength with yield strength and ultimate tensile strength of 203 MPa and 287 MPa, which are 45% and 38% higher than those of matrix (140 MPa and 207 MPa) and 8% and 12% higher than those of uncoated composite (188 MPa and 256 MPa), respectively. The intro-duction of Cu nanoparticles can significantly improve the interfacial bonding strength of Cu-coated composite, ensuring the effective transfer of load from the matrix to carbon nanotubes and exerting its strengthening and toughening effect.