Microstructural evolution and aging behavior of multicomponent Al–Sn–Zn–Mg–Li alloy

• Published in: Journal of alloys and compounds 2025-01, Vol.1011, p.178381, Article 178381
• Main Authors: Seo, Namhyuk, Lee, Sang-Hwa, Lee, Junho, Park, Seonghyun, Kim, Min-Su, Lee, Seok-Jae, Jung, Jae-Gil
• Format: Article
• Language: English
• Subjects: Aluminum alloys; Atom-probe tomography; Precipitation; Transmission electron microscopy
• ISSN: 0925-8388
• DOI: 10.1016/j.jallcom.2024.178381

We investigate the microstructural characteristics and precipitation behavior of a multicomponent Al–Sn–Zn–Mg–Li alloy subjected to solution and aging heat treatments, to provide insights into the alloy design of precipitation-strengthened Al–Sn alloys. Solution treatment at 450 °C causes liquefication of the secondary phase (Mg2Sn, Sn(Zn), and AlLi), forming a spherical Sn-rich phase composed of Sn, Mg2Sn/Mg9Sn5, and Zn phases. Slow furnace cooling (FC) after solution treatment homogenizes the Sn-rich phase and forms coarse Zn precipitates in the Al matrix, producing coarser (∼5 nm) and fewer Zn-rich solute clusters during natural aging (NA). NA of water-quenched (WQ) alloys induces the formation of fine (∼2 nm) Zn-rich clusters (precursor of Zn) and Zn/Mg/Li clusters (precursor of Mg2Zn11) with an average chemical composition of 78.6Al–19.0Zn–1.6Mg–0.8Li (at%), resulting in age-hardening that is superior to that of the FC alloy. Artificial aging (AA) at 90 °C results in the formation of two types of precipitates (major plate-like MgZn2-type lying on {111}Al and minor blocky Mg2Zn11-type), which have lesser hardening effects than the Zn-rich clusters formed during NA. Zn-rich clusters formed during NA improve the hardness of the AA alloys at 90 °C, indicating the beneficial effect of NA at service temperatures. The precipitation-strengthening mechanism of the multicomponent Al–Sn alloy is further discussed based on theoretical strength modeling and analysis precipitate-dislocation interactions. •Multicomponent Al–Sn–Zn–Mg–Li alloys contain Mg2Sn, Sn(Zn), and AlLi phases.•Resolidified Sn-rich phase comprises multiple phases of Sn, Mg2Sn/Mg9Sn5 and Zn.•Natural aging forms very fine coherent Zn-rich and Zn/Mg/Li-rich clusters.•Plate-like MgZn2 and blocky Mg2Zn11 precipitates are formed at 90 °C.•Natural age-hardening response is greater than artificial age-hardening response.