Synergistic Effects of Magnesium Alloying and Graphene Nanoplatelets on the Microstructure and Multifunctional Properties of Bioinspired Laminated Al-30Zn-2Cu Matrix Composites

Inspired by pearl laminates, bioinspired laminated Al-30Zn-2Cu matrix composites with graphene nanoplatelets (GNPs) as the reinforcing phase were successfully prepared in this study, based on flake powder metallurgy combined with the alloying strategy of Mg elements. The effect of Mg alloying on the microstructure, compression property and damping behavior of bioinspired laminated composites was investigated. The result shows that the addition of 1 wt.% of Mg element, the Mg atomic solid solution increased the lattice distortion and warping. And the lath-like η-Zn precipitation phases with high aspect ratio precipitate in the Al {1 1 1} plane. The increase in the number of high aspect ratio η-Zn precipitates, which increases the resistance of the dislocations to cut through or around the precipitates, results in an increase in the external force required for dislocation movement. This results in a greater improvement in both the damping and compression properties of the composites. Concurrently, the incorporation of moderate amounts of Mg element facilitates the densification of the material. However, it has been demonstrated that excessive Mg elements promote the precipitation of rough and continuous Mg₂Cu/MgZn₂ second phase in the grain boundary area. This prevents the formation of fine η-Zn precipitated phases inside the grain, reduces the solid solution strengthening effect, weakens the bonding force at grain boundaries, and leads to the reduction of both damping properties and toughness.