Strong, ductile, and thermally conductive carbon nanotube-reinforced aluminum matrix composites fabricated by ball-milling and hot extrusion of powders encapsulated in aluminum containers

Fumio Ogawa, Shuji Yamamoto, Chitoshi Masuda

Research output: Contribution to journalArticlepeer-review

17 Citations (Scopus)

Abstract

Aluminum matrix composites reinforced by carbon nanotubes (CNTs) were fabricated by ball-milling (with aluminum powder; average diameter 30 µm), followed by hot extrusion of the powders encapsulated in aluminum containers (at 550° with an extrusion ratio of 9). The CNTs were intended to improve the mechanical properties and thermal conductivity of the aluminum composites formed by powder metallurgy. The CNTs were of two types—vapor-grown carbon fibers (VGCFs) with a diameter of 150 nm and multiwalled CNTs (MWCNTs) with a diameter of 65 nm. The composites were evaluated by their Vickers microhardness, tensile strength, and thermal conductivity. The microhardness exceeded 100 HV and increased with increasing volume fraction of reinforcement. The MWCNT-reinforced composites were harder than the VGCF-reinforced composites and exhibited higher ultimate tensile strength (over 450 MPa). The maximum fracture strain (37.2%, observed at a volume fraction of 0.5%) is the highest reported in the literature. Conversely, the VGCF-reinforced composites exhibited higher thermal conductivity than the MWCNT-reinforced composites. The thermal conductivity of the 0.5% VGCF-reinforced composites (203.7 W/m K) also exceeds any previously reported value. In summary, composites with unprecedentedly high ultimate tensile strength, fracture strain, and thermal conductivity were fabricated by a simple process that minimized damage to the CNTs during mixing, protected them from oxidation and excessive reaction with the aluminum matrix and effectively densified composites by hot extrusion.

Original languageEnglish
Pages (from-to)460-469
Number of pages10
JournalMaterials Science and Engineering A
Volume711
DOIs
Publication statusPublished - 2018 Jan 10
Externally publishedYes

Keywords

  • Aluminum matrix composite
  • Ball-milling
  • CNTs
  • Hot extrusion

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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