Multiwalled carbon nanotubes as an additive to Mg-Mg2Si in situ composite obtained by powder sintering

This paper reports on the possibility of applying carbon nanotubes as an additive to metallic materials, where a new phase forms in situ from the powder mixture. Multi-walled carbon nanotubes (MWCNT) amounts of 1 vol% and 3 vol% were applied to synthesize a composite with interpenetrating phases obtained from magnesium microsized powder and nanosized silicon (n)Si by sintering under vacuum. In the ex-periments, two ordered Mg-(n)Si-MWCNT powder mixtures with a (n)Si: MWCNT ratio of 2: 1 were pre-pared by sonication. The effects of Mg2Si silicide in situ synthesis on the behavior of MWCNTs and the Mg2Si and Mg alpha morphology were studied. Using LM with quantitative metallography, SEM with EDS, XRD, HREM, it was found that the MWCNTs were a component of the skeleton formed by submicron and nanosized Mg2Si, MgO, and Mg alpha mixture. Non-agglomerated MWCNTs were also found in microsized Mg2Si particles in the composite. A decrease in the silicide crystallite size was also observed compared with material without a carbon nanocomponent. The transformation of MWCNTs into another phase or their morphology change was not observed. Therefore, the effects described in this paper can be adapted to technologies focused on different types of composites and for designing Mg2Si-based thermoelectric materials and in-termetallic alloys. (c) 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).