Interatomic potential of the MgAl2O4/Al interface and its application in strengthening mechanisms

MgAl2O4 ceramics possess outstanding mechanical properties, making them promising for use as reinforcing or interfacial modulating phase in Al-based metal composites. The challenge lies in the insufficient interatomic potential parameters to accurately characterize the MgAl2O4/Al interfacial interactions, which hampers a detailed understanding of the interfacial strengthening mechanisms at the atomic level. Since the pair potential satisfies the requirements for computational efficiency and accuracy, it has been widely used for investigating the interfacial properties of composite materials. In this study, the interatomic potential parameters for Al–Mg and Al–Al bonds were derived from Buckingham potential, while those for Al–O bonds were obtained from Morse potential via first principles calculations. The uniaxial tensile mechanical properties and interface-dislocation strengthening mechanisms of MgAl2O4/Al interface configuration were explored through molecular dynamics simulations. The analyses reveal that the strength enhancement of the MgAl2O4/Al interface is due to the generation of a large number of immovable 1/6<110> stair-rod dislocations therein. The thickness of MgAl2O4 layer significantly influences the mechanical properties. Below a thickness of 20 Å, the presence of movable dislocations reduces the strengthening effect. Conversely, increasing the thickness of MgAl2O4 encourages the emergence of immovable dislocations and increases the flow stress, while the corresponding yield strain decreases. These insights open up new prospects in the development of aluminum metal matrix composites with enhanced performance.