Abstract: The interfaces between in-situ Al₃Ti particles and magnesium (Mg) matrix are crucial role in high-performance titanium (Ti) reinforced AZ31 alloy. Herein, the interfaces between Al₃Ti particles and the Mg matrix are fabricated and investigated using advanced characterization tools and first-principles calculations. The orientation relationship (OR) and atomic interface structure between the Al₃Ti particles and matrix are characterized using a high-resolution transmission electron microscope. The OR is determined to be (10$\bar{1}$0)_Mg//(001)_Al3Ti; [$\bar{1}$2$\bar{1}$3]_Mg//[100]_Al3Ti. Based on the characterized OR, the interface properties (including atomic structure, work of adhesion, interface energy, and fracture mechanism) are investigated using first-principles calculations. The relaxed interface structure indicates that the TiAl-terminated bridge site configurations (MT1) and hollow site configurations (HCP1) are unstable and would convert into other bridge site configurations (MT). Furthermore, the work of adhesion and interface energy suggests that Al-terminated hollow site configurations (HCP) and bridge site configurations (MT) are more stable than other configurations. In addition, the calculations of work of fracture show that fracture of the interfaces with Al-MT1, Al-HCP, and TiAl-MT configurations may initiate from bulk Mg interior. The findings may help to understand and tailor the deformation mechanisms and mechanical properties of Ti-reinforced Mg alloys.

Key words: Ti/AZ31 alloy, Mg/Al₃Ti interface, HAADF-STEM, First-principles computation