Effect of Zr Additions on the Microstructure and Elevated-Temperature Mechanical Properties of Al–Cu–Mg–Ag–Zn–Mn–Zr Alloys
Open Access
Abstract
This study systematically investigates the influence of Zr additions (0–0.24 wt.%) on the microstructure evolution and mechanical properties of Al–4.0Cu–0.5Mg–0.5Zn–0.5Mn–0.4Ag alloys under peak-aged conditions. Alloys were subjected to homogenization (420 °C/8 h + 510 °C/16 h), solution treatment (510 °C/1.5 h), and aging (190 °C/3 h). Microstructural characterization via OM, SEM, EBSD, and TEM revealed that Zr refines grains and enhances recrystallization resistance through coherent Al3Zr precipitates, which pin grain boundaries and dislocations. However, excessive Zr (0.24 wt.%) induces heterogeneous grain size distribution and significant Schmid factor variations, promoting stress concentration and premature intergranular cracking. Crucially, Al3Zr particles act as heterogeneous nucleation sites for Ω-phase precipitates, accelerating their nucleation near grain boundaries, refining precipitates, and narrowing precipitate-free zones (PFZs). Mechanical testing demonstrated that the Al–4.0Cu–0.5Mg–0.5Zn–0.5Mn–0.4Ag alloy exhibits optimal properties: peak tensile strength of 368.8 MPa and 79.8% tensile strength retention at 200 °C. These improvements are attributed to synergistic microstructural modifications driven by controlled Zr addition, establishing Al–4.0Cu–0.5Mg–0.5Zn–0.5Mn–0.4Ag–0.16Zr as a promising candidate for high-temperature aerospace applications.Keywords
Funding Information
- National Natural Science Foundation of China (52271168, 3072024WD1005, QT1451-0415045, KY11000230049, 2022173)
- Central University Fund (52271168, 3072024WD1005, QT1451-0415045, KY11000230049, 2022173)
- Basic Product Innovation Research (52271168, 3072024WD1005, QT1451-0415045, KY11000230049, 2022173)
- National Science and Technology Project (52271168, 3072024WD1005, QT1451-0415045, KY11000230049, 2022173)
- the Study on Tribology and Lubrication Technology of the Marine Low-Speed Engine (52271168, 3072024WD1005, QT1451-0415045, KY11000230049, 2022173)
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