Nanoceramic particle reinforced high alloying Al-Zn-Mg-Cu composites

In the metal matrix composites (MMCs) reinforced with nanoparticles, the enhancement of composite performance is often closely associated with the types of nanoparticles. It is vital to explore the influences and differences of various nanoparticles on the microstructure evolution and mechanical properties of highly alloyed aluminum-based composites. This study is the first to employ hot pressing for preparing Al-Zn-Mg-Cu composite materials reinforced with SiC and Al₂O₃ nano-ceramic particles, respectively. By employing hot extrusion and T6 heat treatment techniques, a systematic investigation was conducted on the effects of the addition of nano-ceramic particles on the microstructure evolution and mechanical properties of the Al-Zn-Mg-Cu composites, and a comparative analysis was performed on the two types of composite materials. The experimental results demonstrated that the Mg atoms in the α-Al matrix were consumed by the addition of SiC/Al₂O₃ nano-ceramic particles, and thereby the grain size primary η’ (MgZn₂) strengthening phase was refined, leading to an enhanced overall mechanical performance of the Al-Zn-Mg-Cu composite. In particular, the Mg₂Si phase was generated by the addition of SiC nanoceramic particles, through the interfacial reactions, and thus with the synergistic effects of precipitation strengthening and Orowan strengthening, the ultimate compressive strength and compressibility of Al-Zn-Mg-Cu composite can be increased to 844 MPa and 27.5%, respectively. On the other hand, the addition of Al₂O₃ nanoceramic particles can bring about the formation of an oxygen-rich phase and refined precipitates at grain boundaries. Accordingly, the elongation is increased to 43.5% while a high ultimate compressive strength in the composites can be maintained. It is anticipated that nanoceramic particle-reinforced Al-based metal composites have significant potential for achieving both high strength and exceptional ductility for the application in the industry field.