Zn Incorporation within the Intermetallic Mg₁₂(La_xCe_1−x) Lattice in Elektron MEZ

Summary

MEL (Magnesium Elektron) have developed a new magnesium alloy containing a rare earth misch metal, Zn and Mn (designated Elektron MEZ). This alloy has superior high temperature creep properties compared to AE42, and shows potential for both HPDC and sand casting applications. The sand cast microstructure is comprised of equiaxed dendrites of a Mg solid solution separated by an intermetallic interdendritic phase. In this work systematic electron diffraction and analytical electron microscopy studies are used to identify the crystal structure and composition of this interdendritic phase. Variations in emission rates of characteristic X-rays, resulting from high energy electrons systematically scanned in angle of incidence near a zone axis orientation, are used to form two-dimensional channelling patterns. When this experimental data is used in conjunction with calculated channelling patterns for the specific crystal structure, characteristic features associated with individual sublattice or interstitial sites can be identified. This is particularly useful in enabling the specific sublattice site for minority atomic species to be determined. In this paper, channelling patterns are used to identify the particular type of sublattice site occupied by the minority Zn atoms within the intermetallic interdendritic phase.