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Effect of cooling rate on growth and transformation of primary Mg2Si in Al–Mg2Si in situ composites

  • Dongtao Wang (a1), Haitao Zhang (a1), Cheng Guo (a1), Hailin Wu (a1) and Jianzhong Cui (a1)...


In this paper, the morphology transition and the growth process of the primary Mg2Si in the Al–Mg2Si in situ composites were three-dimensionally investigated by observing the extracted Mg2Si particles. The primary Mg2Si transforms from perfect octahedron to truncated octahedron with increasing cooling rate. Combining with the crystal morphologies obtained at different growth stages, the growth mechanism of octahedral Mg2Si was discussed. In the early growth stage of the octahedral Mg2Si, the secondary branches preferentially grow on the advancing tips of the first branches. Then, the hollows in the {111} faces shrink gradually and the octahedral Mg2Si forms finally. With the increase of Mg2Si content, dendritic Mg2Si phases were observed and the truncated octahedron Mg2Si connect mutually to form the complicated morphology at low cooling rate. The high cooling rate transforms the morphology of the Mg2Si crystal. The growth rates of the 〈100〉 and 〈111〉 axes can be manipulated by adjusting the cooling rates, which are responsible for the evolution of the Mg2Si crystals.


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Effect of cooling rate on growth and transformation of primary Mg2Si in Al–Mg2Si in situ composites

  • Dongtao Wang (a1), Haitao Zhang (a1), Cheng Guo (a1), Hailin Wu (a1) and Jianzhong Cui (a1)...


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