Characterisation of magnesium oxide and its interface with α-Mg in Mg-Al-based alloys

Y. Wang, Z. Fan, X. Zhou, G. E. Thompson

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Magnesium oxide (MgO) films and particles have been collected by pressurised filtration of a Mg-8.6wt%Al-0.67wt%Zn (AZ91D) alloy melt. The morphology of the oxides and their interfaces with the-Mg phase were investigated by high-resolution transmission electron microscopy. It was found that the oxide films consisted of large numbers of sub-micrometre-sized MgO particles, and that melt shearing can effectively break up the oxide films and disperse the oxide particles. For the first time, orientation relationships (ORs) of OR I: [1 1̄ 1]MgO2 from (0 0 0 1)α-Mg and (0 1 1)MgO//[2 1̄ 1̄ 0)α-Mg; and OR II: (1̄ 1̄ 1)MgO//(1 1̄ 0 1)α-Mg and [0 1 1]MgO//[1̄ 2 1̄ 1̄]α-Mg, were observed between the MgO particles and the α-Mg matrix. The calculated Bramfitt planar disregistries were 5.5% and 2.5% for the two ORs, respectively, indicating good lattice matching between MgO and α-Mg at the interface. With the evidence of grain refinement effect observed in the sheared AZ91D magnesium alloy, the possibility of MgO particles to act as potent nucleants for heterogeneous nucleation of α-Mg grains is discussed in terms of the crystallographic criterion. © 2011 Taylor &Francis.
    Original languageEnglish
    Pages (from-to)516-529
    Number of pages13
    JournalPhilosophical Magazine Letters
    Volume91
    Issue number8
    DOIs
    Publication statusPublished - Aug 2011

    Keywords

    • interface
    • magnesium alloys
    • magnesium oxide
    • transmission electron microscopy

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