Multi-walled carbon nanotube-reinforced magnesium alloy composites

Abstract

This study demonstrates the ability to fabricate lightweight, ductile but mechanically strong magnesium alloy (AZ91D) composites by introducing a small number of high crystalline multi-walled carbon nanotubes. It is demonstrated that 1 % of relatively short and straight carbon nanotubes distributed homogeneously on the outer surface of magnesium powders act as an effective reinforcing filler to prevent deformation, thereby contributing to the enhanced tensile strength of magnesium alloy composites (e.g., from 315 to 388 MPa).Keywords: Carbon nanotubes; Magnesium alloy; Powder processing; Mechanical property There has been strong recent interest in developing lightweight and high-strength materials to improve the energy-efficiency through the weight reduction of automobiles and aircrafts. For these purposes, magnesium alloys have attracted a lot of attention [1-3], as they have low density in its purest form, and in addition, they have been proved to have good mechanical properties through the incorporation of structural filler (e.g., silicon carbide whisker, aluminum and graphite particles, and carbon fibers) [4][5][6][7]. Within this context, the dimensionally nano-sized, mechanically strong, electrically and thermally conductive carbon nanotubes [8][9][10][11], considered to be the ideal reinforcing filler in various composite systems [12][13][14][15], have been incorporated into magnesium matrix [16][17][18][19]. Recently, Goh et al. [19] reported a simple way of preparing nanotube-reinforced magnesium composite by powder-powder mixing and subsequent hot extrusion processes. However, low enhancement (only 5 %), or even a decrease in, tensile strengths in nanotube-reinforced magnesium composites (see Table 3 in ref. 19) could be explained by the presence of aggregated carbon nanotubes within a magnesium matrix. To exploit carbon nanotubes fully as a mechanical reinforcing filler in a magnesium matrix, optimized fabrication processes including homogeneous dispersion of carbon nanotubes must be 1

Characteristics of powder metallurgy pure titanium matrix composite reinforced with multi-wall carbon nanotubes

“…Previous studies indicated characteristics of the metal matrix composites (MMCs) reinforced with CNTs, where industrial metals such as aluminum, magnesium, nickel, copper and their alloys were used [5][6][7][8][9][10][11][12][13][14]. Titanium (Ti) and titanium alloy are also interested as the matrix material because they are widely used in various industrial applications, for example, automotive, motorcycles, and airplane industries due to their high specific strength and Young's modulus.…”

An anticorrosive magnesium/carbon nanotube composite

“…In addition, several significant studies showed that the introduction of carbon nanotubes resulted in lightweight composites with enhanced mechanical strength. [7][8][9][10][11] In particular, we proved that the short, linear and well-ordered MWNTs directly contributed to 25 and 11 % increases in the elastic modulus and tensile strength of magnesium alloy composites, respectively. 11 From these results, we envisage that MWNTs-filled magnesium composites are possibly the best candidates for constructing lightweight materials for automobiles, always considering an energy-efficient environment.…”

“…[7][8][9][10][11] In particular, we proved that the short, linear and well-ordered MWNTs directly contributed to 25 and 11 % increases in the elastic modulus and tensile strength of magnesium alloy composites, respectively. 11 From these results, we envisage that MWNTs-filled magnesium composites are possibly the best candidates for constructing lightweight materials for automobiles, always considering an energy-efficient environment. We believe that nanotube-filled magnesium alloy composites could replace aluminum alloys in some commercial markets and will boost the replacement of engineering plastics where the components with lightweight, hardness and mechanical strength are required.…”

“…11 Fine-grained powder (average grain size: 100 μm) magnesium alloy (AZ91D) was prepared using tri-axial vibrating-type ball miller (TKMAC-1200L, 10 mmφ zirconia ball, argon atmosphere) at 800 rpm for 6 hours.…”

“…Since the inclusion of MWNTs improves 5 the mechanical properties of magnesium alloy as well 11 , optimizing the MWNTs dispersion, type, length and diameter of MWNTs used in MWNTs/magnesium alloy composite, would further improve the corrosion resistivity and high mechanical properties at the same time. Our results could be considered as a breakthrough and will develop applications of a light metal such as magnesium, which, by an innovative process of incorporating MWNTs, becomes mechanically strong and anticorrosive.…”