Growth orientations and morphologies of α-Mg dendrites in Mg–Zn alloys

Dendritic growth orientations and three-dimensional morphologies of hexagonal close-packed α-Mg(Zn) solidification microstructures were studied in an Mg–Zn alloy with a high Zn content. Using a combination of electron backscatter diffraction and X-ray synchrotron tomography, we have demonstrated that α-Mg(Zn) dendrites grow with a six secondary branched structure behind the advancing dendrite tip. The crystallography of the branches and advancing dendrite is discussed.