Magnetic, Electrical, and Mechanical Behavior of Fe-Al-MWCNT and Fe-Co-Al-MWCNT Magnetic Hybrid Nanocomposites Fabricated by Spark Plasma Sintering

Abstract

This paper aims to investigate different properties of the Fe-Al matrix reinforced with multi-walled carbon nanotube (MWCNT) nanocomposites with the Al volume content up to 65%, according to the Fe-Al combination. In addition, the effect of adding Co content on the improvement of the soft magnetic properties of the nanocomposites was carried out. The nanocomposites were fabricated using the powder metallurgy process. The iron-aluminum metal matrix reinforced multi-walled carbon nanotube (Fe-Al-MWCNT) nanocomposites showed a continuous increase of saturation magnetization from 90.70 A·m2/kg to 167.22 A·m2/kg and microhardness, whereas the electrical resistivity dropped as the Al content increased. The incorporation of Co nanoparticles in Fe-Al-MWCNT up to 35 vol% of Co considerably improved the soft magnetic properties of the nanocomposites by reducing the coercivity and retentivity up to 42% and 47%, respectively. The results showed that Al-based magnetic nanocomposites with a high Al volume content can be tailored using ferromagnetic particles. The composites with a volume content of magnetic particles (Fe+Co) greater than 60 vol% exhibited higher saturation magnetization, higher coercivity, and higher retentivity than the standard Sendust core. Moreover, the produced composites can be used for the lightweight magnetic core in electromagnetic devices due to their low density and good magnetic and mechanical properties.

The Effect of the Processing Parameters on the Properties of the Liquid Phase Spark Plasma Sintered 80Fe-20(Al + MWCNT) Magnetic Metal Matrix Nanocomposites

“…It is believed that the polished areas of the samples were sensitive to the oxidation after being exposed to the air, especially the area of melted aluminum. This was different from the previous study on the Fe-Al-MWCNT nanocomposites that were sintered at 600 °C where the oxidation tended to occur on the surface of iron area and the solid aluminum particles were clearly and distinctively separated from iron particles and MWCNT [16,18]. Additionally, the existence of oxygen in the materials may be resulted from the contamination during the ball milling The dispersion of each component was observed using EDS mapping and the images are shown in Figure 3e,f.…”

“…It can be seen that all composites exhibited about twofold higher resistivity than the pure iron compact. These results were in good agreement with the fact that the addition of a small amount of Al in the Fe matrix would result in material with improved electrical resistivity [13,[16][17][18]. A decrease in electrical resistivity of the composites was observed as the result of increasing the volume content of MWCNT.…”

“…The magnetic and mechanical properties of the composites were analyzed according the processing parameters such as the MWCNT content and ball milling time and post-sintering heat treatment. In fact, in the previous study by the authors [16,18], the Fe-Al-MWCNT magnetic hybrid nanocomposites (with Fe content up to 70 vol%) sintered at 600 °C has shown the composites to have high magnetic coercivity (greater than 5000 A/m) making the materials magnetically hard. The intention of the present paper is to produce the relatively softer magnetic nanocomposite materials with lower coercivity.…”

Optimization of MWCNTs/Al nanocomposite fabrication process parameters for mass density and hardness

“…From the XRD data, the formation of the f-MWCNTs/Al nanocomposite is confirmed. 67 The average crystallite size of Al for trial run 3 is 53.08 nm and it is calculated using the Debye-Scherrer formula. 68 Figure 3 (c) shows the XRD pattern for trial run 6.…”