Optimization of fine-grained powder addition for strengthening and wear resistance in heterostructured 2219 Al alloys fabricated by powder metallurgy

High-performance 2219 Al-Cu alloys are urgently required for lightweight aerospace structures, yet conventional powder metallurgy alloys often show limited strength–ductility synergy and inadequate wear resistance. In this study, heterogeneous grain-structured 2219 Al-Cu alloys were fabricated by introducing different contents of high-energy ball-milled fine-grained 2219Al powder into the original powder matrix, followed by rapid hot pressing sintering. The effects of fine-grained powder (FP) content on microstructural evolution, densification, mechanical properties, and tribological behavior were systematically evaluated. The results show that ball milling refined the 2219Al powder and increased its surface activity, promoting sintering densification and grain structure regulation. With increasing FP content, a fine-grain-surrounded coarse-grain heterogeneous structure was gradually formed. The optimal overall performance was attained by the alloy with 3 wt.% FP, which displayed a relative density of 98.47%, a hardness of 63.54 HB, a tensile strength of 300 MPa, and an elongation of 10.6%. Its wear rate decreased to 2.83 × 10 ⁻²  mm ³ ·N ⁻¹ ·m ⁻¹ , 28.7% lower than that of the unmodified alloy. This study demonstrates a simple and effective fine-powder engineering strategy for constructing heterogeneous grain structures in powder metallurgy 2219 Al-Cu alloys, providing a feasible route to simultaneously enhance mechanical properties and wear resistance without introducing external ceramic reinforcements.