Effects of Cu, Si and Mg additions on the interfacial properties and mechanical properties of Be/Al composites: First-principles calculations and experimental studies

Interface bonding strength plays a crucial role in enhancing the mechanical performance of beryllium/aluminum composites. In this study, the effects of Cu, Si and Mg doping on the interfacial properties of Be/Al composites were studied from the aspects of interfacial adhesion work and interfacial electronic structure through firstprinciples calculations based on density functional theory (DFT), and the Be/Al and Be/Al-5Cu-1.5Mg-0.2Si composites were prepared to verify the segregation behavior of doping elements at the interface and the effects of alloying elements addition on the interface bonding strength and mechanical properties. The firstprinciples calculation results reveal that the doping of Cu increases the interfacial adhesion work and strengthens the bonding between Be and Al atoms at the Be/Al interface, which leads to an enhancement of the bonding strength in the Al/Be interface. Si is found to have a beneficial effect on the interface bonding, albeit with a relatively minor influence. Conversely, the doping of Mg decreases the adhesion work of the Be/Al interface, as Mg forms anti -bonding with Be, thus being detrimental to the interface bonding. Energy spectrum analysis conducted on the near -interface region of the Be/Al-5Cu-1.5Mg-0.2Si composite reveals that Cu exhibits significant segregation at the Be/Al interface, Si exhibits a minor degree of segregation at the interface, while Mg does not show any significant segregation at the interface and is mainly distributed in Al matrix. Moreover, from the experimental comparison of interface bonding strength and mechanical performance between the two composites, it is evident that the addition of alloying elements (Cu, Mg, Si) effectively enhances the interface bonding and significantly improves the strength and ductility of the beryllium/aluminum composite. Combined the calculation and experimental results, it can be concluded that the enhancement of the bonding strength at the beryllium/aluminum interface is primarily driven by the addition of Cu, with a minor contribution from Si. Meanwhile, Mg strengthens the beryllium/aluminum composite mainly by strengthening the aluminum phase. This study provides an effective approach for enhancing the mechanical performance of beryllium/aluminum composites by regulating the interface bonding strength through matrix alloying.