A First-principles Study on the Adhesion Strength, Interfacial Stability, and Electronic Properties of Mg/Mg₂Y Interface

The interfacial microstructures and configurations directly affect the comprehensive properties of the composites, but their interfacial adhesion mechanism is complicated to expound by experimental methods. In this work, based on the stacking sequence of the Mg/Mg2Y interface models, nine different Mg/Mg2Y interface configurations with top site, bridge site, and hollow site (HCP) under Mg1, Mg2, and Y terminations were successfully constructed and systematically explored by first principles calculations. The results showed that the Mg2Y(0001) surface with Y termination is the most stable when the yttrium chemical potential (Delta mu(Y)) is less than - 1.09 eV; otherwise, Mg2Y(0001) surface with Mg1 termination is the most stable. The seven-layer Mg(0001) and eleven-layer Mg2Y(0001) slabs are employed to reflect the bulk-like interior properties. Additionally, the Mg(0001)/Mg2Y(0001) with the Y-HCP stacking has the largest interface thermodynamic stability with the value of 2.383 J/m(2) in all interface configurations owing to its largest work of adhesion. In addition, the interfacial energy of Y-HCP stacking is significantly smaller than those of Mg1-HCP when Delta mu(Y) is approximately less than - 0.55 eV, showing that it is more stable. The thermodynamic stability of Mg/Mg2Y with Y-HCP is due to Mg-Y chemical bonds formed between Mg and Y atoms. Lastly, the Mg/Mg2Y interfaces are strong interfaces based on the Griffith fracture theory.