Mechanical properties and strain hardening behavior of aluminum matrix composites reinforced with few-walled carbon nanotubes

• Published in: Journal of alloys and compounds 2020-06, Vol.826, p.154075, Article 154075
• Main Authors: Chen, B., Li, Z., Shen, J., Li, S., Jia, L., Umeda, J., Kondoh, K., Li, J.S.
• Format: Article
• Language: English
• Subjects: Aluminum; Aluminum base alloys; Aluminum matrix composites; Ball milling; Carbon; Carbon nanotubes (CNTs); Densification; Dislocation density; Ductility; Elongation; Hot extrusion; Mechanical properties; Metal matrix composites; Metal matrix composites (MMCs); Multi wall carbon nanotubes; Necking; Plasma sintering; Plastic deformation; Powder metallurgy; Spark plasma sintering; Strain hardening; Strength; Structural integrity; Tensile strength; Tubes
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2020.154075

In this study, for the first time few-walled carbon nanotubes (FWCNTs) with ∼3 walls were used as reinforcements in fabricating high performance aluminum matrix composites (AMCs). FWCNTs/Al composites and referential Al materials were prepared by a powder metallurgy route consisting of high energy ball milling, spark plasma sintering (SPS) and subsequent hot extrusion. It is found that, by decreasing SPS temperature and time, FWCNTs/Al composites showed reduced grains with an increased dislocation density and improved structural integrity of FWCNTs, leading to an increased tensile strength. Meanwhile, comparatively high strain hardening rates and long strain softening behavior were observed after necking in the sample sintered at 500 °C, which resulted in a tensile elongation of 11.7% with a high yield strength of 382 MPa. The experimental results suggested that, compared with traditional multi-walled carbon nano-tubes (MWCNTs), FWCNTs showed a noticeably enhanced strengthening effect and provided a good balance of strength and ductility in Al composites. It may make FWCNTs a good reinforcement candidate for metal matrix composites to achieve improved mechanical properties. •For the first time FWCNTs were used as reinforcements in Al matrix composites.•FWCNTs/Al have long strain softening stage after necking.•FWCNTs/Al sintered at 500 °C has yield strength of 382 MPa and tensile elongation of 11.7%.•FWCNTs have better strengthening effect than MWCNTs.