Research Progress on Post-processing Technology and Microstructure Control of Al-Cu High-Strength Cast Aluminum Alloys

Al-Cu high-strength cast aluminum alloys possess low density, high specific strength, and excellent heat treatment strengthening potential, making them valuable for applications in aerospace, defense, and high-end equipment manufacturing. However, these alloys are prone to microstructural defects such as porosity, shrinkage porosity, dendritic segregation, and coarse second phases under as-cast conditions, leading to decreased strength, plasticity, fatigue performance, and corrosion resistance. Post-treatment processes are crucial for improving as-cast defects, controlling precipitation behavior, and enhancing overall performance. This paper reviews the influence of three typical post-treatment processes—hot isostatic pressing (HIP), solution treatment, and aging treatment—on the microstructure evolution and performance regulation of Al-Cu high-strength cast aluminum alloys. The paper focuses on analyzing the mechanisms of defect compaction during HIP, homogenization of the solution-treated microstructure, and precipitation strengthening during aging. Furthermore, it elucidates the impact of microstructure on mechanical properties, fatigue performance, and corrosion resistance from the perspectives of defect characteristics, intragranular precipitates, grain boundary precipitates, and second-phase distribution, providing a reference for the design of post-treatment processes and the synergistic optimization of microstructure and properties in Al-Cu high-strength cast aluminum alloys.