Syntheses, microstructure evolution and performance of strength-ductility matched aluminum matrix composites reinforced by nano SiC-cladded CNTs

Abstract Nano SiC layer is innovatively introduced into carbon nanotubes/Al (CNTs/Al) interface to improve the interface bonding and control the interface reaction between CNTs and Al matrix. SiC-cladded CNTs (CNTs@SiC) reinforced aluminum matrix composites (AMCs) were prepared by variable speed ball milling process-powder metallurgy-hot extrusion route. The results show that the introduction of SiC layer hinders the occurrence of interfacial reaction between CNTs/Al and inhibits the formation of Al4C3 brittle phase which should improve the structural stability of AMCs. The dispersive CNTs@SiC reinforcements play an effective pinning role in the sintering process of AMCs at high temperature, which inhibits the growth and mergence of Al matrix grains. Nano SiC transition layer transforms the reactive interface of CNTs/Al4C3/Al into the diffusion and mechanical interface of CNTs/SiC/Al, which improves the wettability and interface bonding between Al matrix and CNTs@SiC reinforcements. It also acts as a firm bridge to transfer physical information such as stress and phonon, which effectively promotes the load transfer efficiency between Al and CNTs. Accordingly, the tensile strength and elongation of 0.5CNTs@SiC-Al reach 190 MPa and 22.9 %, which shows further improvement in strength-ductility matching for CNTs reinforced AMCs while maintaining the good electrical conductivity and structural stability of Al matrix.