Processing of CNTs Reinforced Al‐Based Nanocomposites Using Different Consolidation Techniques

Abstract

In this work, the development of two types of Al-based alloys with different concentrations of Si reinforced with MWCNT’s at 0.5–2.0 wt% is presented. Sonication of the CNT’s in ethyl alcohol was carried out for dispersion, and the mixtures were ball milled for 1, 3, and 5 hrs. SEM/EDS were used to study the morphology and the effects of changing milling parameters in addition to changes caused due to increasing concentration of the CNT’s. Furthermore, three sintering techniques, namely, Spark Plasma Sintering (SPS), Microwave Sintering (μWS), and Hot Isostatic Press Sintering (HIP) were employed to consolidate the ball milled powders at varying temperatures of 400, 450, and 500°C. It was found that SPS consolidated samples showed the most promising results amongst the three with the highest hardness values; around 100% densification, as well as the finest microstructure. On the other hand, microwave sintered samples showed the least appealing results, this could be attributed to the poor temperature distribution and the pressureless nature of the technique. A sintering temperature of 500°C was found to be the most suitable for these types of alloys.

Nanocrystalline Al7075 + 1 wt % Zr Alloy Prepared Using Mechanical Milling and Spark Plasma Sintering

“…It is believed that, beside the applied pressure, local electric and magnetic fields can activate the powder’s surface, help to break up and remove oxide layers present on the surface of powder particles handled without an inert atmosphere, and promote full densification. Our results confirmed (in accordance with previous experiments on other Al-based alloys [ 20 , 21 , 38 , 39 ]) that SPS is very efficient in the preparation of compacts with nearly full density. The slightly lower density of the Al7075Zr_AC compact (as compared to the theoretical value) may be caused by the presence of some retained oxide particles rather than by porosity.…”

“…Both gas atomized (e.g., [ 11 , 12 , 13 , 14 , 15 ]) and milled (e.g., [ 16 , 17 , 18 , 19 ]) powders have been sintered by a variety of methods. SPS results in the lowest porosity [ 20 ], and is also very efficient in the production of a very fine-grained microstructure [ 19 , 20 ]. Numerous experiments have been performed on the 7xxx series of Al-based alloys.…”

Effect of Processing on Mechanically Alloyed and Spark Plasma Sintered Al‐Al2O3 Nanocomposites

“…The composite reinforced with 10% vol. of Al 2 O 3 nanoparticles displaced higher hardness than other aluminium based nanocomposites reinforced with CNTs [46][47][48] or SiC nanoparticles [33]. However, its hardness was lower than the hardness of Al-10 wt.% SiC nanocomposite [15] and Al5083-10 wt.% SiC [39].…”

The Influence of Milling and Spark Plasma Sintering on the Microstructure and Properties of the Al7075 Alloy

“…There are many investigations on Al-based materials showing that spark plasma sintering is a very efficient technique for preparation of bulk materials with a very low porosity [ 28 , 29 , 30 ]. The sintering temperature and applied load are the most important parameters influencing both the resulting porosity and the microstructure of the sintered compact.…”