Interfacial properties and fracture behavior of β"/Mg interface in Mg–La alloy: A first-principles study

A deeper investigation into the characteristics of the β"/Mg interface represents a promising strategy for improving the ductility and strength of Mg–La alloys. This study systematically investigates the interface adhesion, stability, electronic structure, and tensile fracture behavior of three β"/Mg interfaces with different orientations through the first-principles method. The results indicate that the Mg1-T4-β"(1‾ 010) interface has the strongest binding capacity, and the atomic arrangement at the interface is consistent with the observation results from previous studies using HAADF-STEM. The PDOS and CDD analysis reveal differences in the atomic orbital hybridization, resulting in the formation of Mg–Mg homometallic bonds and Mg–La heterometallic bonds, contributing to the interface strength. The three interfaces exhibit varying mechanical properties with different strengths and strains, influenced by orientation and arrangement of atoms. The fractures occur near the La atom at the interface when the strain reaches a certain level due to insufficient bonding strength between Mg and La. The ductility of the β" precipitate is critical to the interface's ability to undergo plastic deformation. These findings offer new insights into the precipitate interface of Mg–La alloy and could guide the optimization of its properties for various applications.