Atomic-Scale Insight into Structure and Interface of Al2Y Phase in an Mg-Al-Y Alloy

Atomic-scale structure of Al2Y phase and its interface with magnesium matrix in an Mg-1Al-6.2Y (wt%) alloy have been investigated using scanning transmission electron microscopy (STEM) and density-functional theory (DFT). Apart from micro-sized Al2Y particles in the interior of grains or along grain boundaries, nano-sized Al2Y lamella with a large aspect ratio precipitates within the grains. Y - enriched stacking faults are introduced at the lamellar Al2Y/Mg interface due to 0.07% lattice misfit between (022)(Al2Y) and (0 (1) over bar 10)(Mg) planes. The first-principles simulation clarifies that Al2Y/Mg interface is energetically occupied by Al atoms other than Y atoms.