Effect of interfacial BeO content on microstructure and mechanical properties of beryllium/aluminum composites

In metal matrix composites, the existence of the interface phase imparts a complex influence on the interface bonding of the composites, while robust interfacial bonding is imperative for efficacious load transfer, which plays a crucial role in improving the mechanical properties of the composites. The purpose of this study is to investigate the effect of interface BeO content on the interfacial bonding strength and mechanical properties of Be/Al composites. Two types of Be/Al composites were prepared by self-exhausting pressure infiltration method, one of which was preheated in air atmosphere and the other was preheated under argon protection. Microstructural analysis results showed that significant oxidative corrosion occurred on the surface of beryllium particles in the Be/Al composite preheated in air atmosphere, and a considerable amount of oxide existed at the Be/Al interface, forming an oxide layer with oxide beryllium nanoparticles with particle sizes of 20∼50 nm. The interface of the Be/Al composite preheated under inert atmosphere was the direct combination of beryllium phase and the aluminum phase, with a few localized areas containing a small amount of aluminum oxide. Furthermore, mechanical property tests showed that the Be/Al composite preheated under inert atmosphere exhibited better mechanical properties and higher interfacial bonding strength. The first-principle simulation results further confirmed that the low interfacial bonding strength of the Be/Al composite preheated in air atmosphere was due to the much lower adhesion work of the BeO/Al interface than that of the Be/Al interface, and no bonding trend was observed between BeO and Al. The results of this study indicate that the presence of an abundance of interfacial BeO can lead to the deterioration of the Be/Al interface bonding, and avoiding the production of interfacial BeO is crucial in obtaining better interfacial bonding. These findings point out the direction for the design and preparation of high-performance Be/Al composites.