Interface regulation strategy of Al-CNTs composite induced by Al-Si eutectic reaction and its strengthening mechanism

Carbon nanotubes (CNTs) reinforced aluminum matrix composites (AMCs) show broad application prospects in the fields of aerospace and transportation because of their lightweight, high specific strength and specific modulus. A new alloying strategy in this study is proposed to regulate its weak intrinsic interface and uncontrollable interfacial reaction. Our results show that Si element could hinder the dissolution and diffusion of carbon atoms in Al matrix, inhibiting Al-CNTs interface reaction. Grain refinement and dislocation increment induced by the reinforcements promote the contributions to the strength of AMCs. The wettability and interface bonding of Al-CNTs could be effectively improved by Al/Si/CNTs composite interface, the formed discontinuous strong interface is advantageous to coordinate the plastic deformation of AMCs. Si particles can also firmly fix CNTs through pinning effect during deformation, which leads to a better load transfer. Therefore, the tensile strength of Al-5Si-0.5CNTs composite can be enhanced up to 391 MPa while maintaining an acceptable plasticity of 7.5%. It brings the strengthening effect of CNTs into full play in AMCs and achieves the strengthening effect of 1+1>2 under the comprehensive effect of grain refinement strengthening, dislocation strengthening, dispersion strengthening of Si particles and load transfer to CNTs.