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The influence of nanoparticles on dendritic grain growth in Mg alloys

Guo, E; Shuai, S; Kazantsev, D; Karagadde, S; Phillion, AB; Jing, T; Li, W; (2018) The influence of nanoparticles on dendritic grain growth in Mg alloys. Acta Materialia , 152 pp. 127-137. 10.1016/j.actamat.2018.04.023. Green open access

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Abstract

Melt processing offers a cost effective method for producing metal matrix nanocomposite (MMNC) components; however, the influence of nanoparticles on the evolving microstructure during solidification is still not well understood. In this study, the effect of SiC nanoparticles on α-Mg dendrite evolution in a Mg-25Zn-7Al (wt.%) alloy was investigated through 4D (three dimensions plus time) synchrotron tomographic quantification of solidification experiments conducted at different cooling rates with and without nanoparticles. Key features of the solidifying primary α-Mg dendritic grains were quantified, including grain morphology, size distribution, and dendrite tip velocity. To obtain the high-contrast tomography dataset necessary for structure quantification, a new image reconstruction and processing methodology was implemented. The results reveal that the addition of nanoparticles increases grain nucleation whilst restricting dendritic growth and altering the dendritic grain growth morphology. Using LGK model calculations, it is shown that these changes in solidification microstructure occur as a result of nanoparticle-induced restriction in Zn's effective diffusivity ahead of the dendrite tips, reducing tip velocity. The results both suggest the key phenomena required to be simulated when numerically modelling solidifying Mg-based MMNC and provide the data required to validate those models.

Type: Article
Title: The influence of nanoparticles on dendritic grain growth in Mg alloys
Open access status: An open access version is available from UCL Discovery
DOI: 10.1016/j.actamat.2018.04.023
Publisher version: https://doi.org/10.1016/j.actamat.2018.04.023
Language: English
Additional information: This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: Metal matrix nanocomposites, Dendritic solidification, Nanoparticles, Tomography, Iterative image reconstruction
UCL classification: UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Mechanical Engineering
URI: https://discovery.ucl.ac.uk/id/eprint/10049187
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