Characterization of Al2024-CNTs composites produced by mechanical alloying

In the present work, the 2024 aluminum alloy (Al2024) alloy has been produced by mechanical alloying (MA). The alloy was then strengthened by dispersion of carbon nanotubes (CNTs) during different times. Thus, the effect of CNTs concentration and milling time on the microstructure of the Al2024-CNTs composites was studied. The results show a homogeneous dispersion of CNTs into the Al-matrix phase by mechanical milling (MM). It was observed that the increment in the milling time, for a fixed amount of CNTs, causes a reduction of the particle size of powders resulting from MA. The finest particle size was obtained at 20 h of milling. These observations were confirmed by scanning and transmission electron microscopy. After 10 h of milling, Cu, Mg and other alloying elements constituting the Al2024 alloy, form a solid solution and only some remnant Mn particles were observed but not detected by X-ray diffraction.

Graphical abstractCNTs were dispersed in the 2024 aluminum alloy by means of mechanical milling. CNTs were added in several concentrations (0.5–5.0 wt.%) and the milling time for the CNTs dispersion was o 0–30 h. XRD spectra indicates the formation of a solid solution after 10 h of milling. The presence of the carbon reflections in XRD patterns is not observed for all milling conditions mainly due to the nanometric size of the reinforcing phase of the composites. A homogeneous particle size was achieved from 5 h of milling. MEB displays a dramatic change in the particle size as function of the CNTs content.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► By Mechanical alloying can produced Al-CNT composites. ► CNTs are well dispersed into Al matrix. ► CNTs content have an important effect over final particle size and morphology. ► CNTs keep their morphology after milling process.