HAADF-STEM observation of unique quasicrystalline precipitates from solid solution in Mg-Cd-Yb system

We found that solid-solution and aging treatments could promote precipitation of fine quasicrystal (Qc) particles in the Mg matrix of the Mg-Cd-Yb system. Precipitated Qc particles in the Mg matrix possess clear facets showing a rectangular shape along the a-axis direction of Mg, and irregular hexagons or rectangles with twinning along the Mg c-axis direction. These Qc precipitates and surrounding Mg matrix have a specific orientation relationship and planer interfaces composed of Qc{2-f} and Mg{10-10}, Qc{5-f} and Mg{10-10}, Qc{2-f} and Mg(0002), where {2-f} and {5-f} indicate the two-fold and five-fold planes, respectively. High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) revealed excellent matching of the Qc{2-f} and Mg(0002) on the Qc{2-f}/Mg{10-10} interface. We discussed these precipitation behaviors and the twinning of Qc from the viewpoint of the specific relationships and the stable interface between Qc and Mg.

Automated summary

Solid-solution and aging treatments can promote the precipitation of fine quasicrystal particles in the Mg matrix of the Mg-Cd-Yb system. The specific orientation relationship and stable interface between Qc and Mg contribute to the twinning and precipitation behaviors of Qc. High-angle annular dark-field scanning transmission electron microscopy reveals excellent matching of the Qc and Mg on the interfaces.