Enhancing mechanical properties of Al-Zn-Mg-Cu alloys: The impact of high strain rate compression and subsequent heat treatment on microstructural evolution

This study presents a comprehensive examination of the Al-Zn-Mg-Cu alloy, focusing on the effects of high strain rate dynamic compression and heat treatment on its performance. The research aimed to understand the underlying microstructural mechanisms contributing to the enhanced mechanical properties of the alloy, which is critical for applications in aerospace and automotive industries. High strain rate dynamic compression tests, conducted at 3.0 × 1000 s⁻¹, revealed a significant increase in both yield strength and ultimate compression strength of the Al alloy, which was accompanied by a increase in hardness. Post-compression microstructural analyses utilizing transmission electron microscopy and scanning- transmission electron microscopy indicated that significant changes occurred during testing. Key findings include the development of micro shear bands, alterations in the size and distribution of precipitates, and the emergence of new plate-like precipitate formations. Subsequent T6 heat treatment led to further microstructural evolution, particularly impacting the volume fraction and size of η' precipitates. The study highlights the crucial role of dislocation-precipitate interactions, where dislocations are effectively pinned by precipitates, thereby contributing significantly to the material's strength. These results demonstrate the potential of high strain rate dynamic compression coupled with heat treatment as a method to significantly enhance the mechanical properties of Al-Zn-Mg-Cu alloys. Overall, the findings provide valuable insights into the optimization of this alloy for high-performance applications, emphasizing the importance of controlled microstructural engineering.