Effect of Natural Aging on the Artificial Aging Behavior of a New Al-Zn-Mg-Cu Alloy

doi:10.11900/0412.1961.2025.00184

Acta Metall Sin

2026, Vol. 62

Issue (2): 383-396 DOI: 10.11900/0412.1961.2025.00184

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Effect of Natural Aging on the Artificial Aging Behavior of a New Al-Zn-Mg-Cu Alloy

JIANG Lei¹, ZHOU Taiwentao², ZHANG Xinbiao², XIAO Xingyu², ZHANG Zhihao¹^,²^,³^,⁴(

), XIE Jianxin¹^,²^,³^,⁵

1 School of Advanced Materials Innovation, University of Science and Technology Beijing, Beijing 100083, China
2 Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083, China
3 Key Laboratory for Advanced Materials Processing (MOE), University of Science and Technology Beijing, Beijing 100083, China
4 Institute of Materials Genome Engineering, Henan Academy of Sciences, Zhengzhou 450046, China
5 Institute of Materials Intelligent Technology, Liaoning Academy of Materials, Shenyang 110004, China

Cite this article:

JIANG Lei, ZHOU Taiwentao, ZHANG Xinbiao, XIAO Xingyu, ZHANG Zhihao, XIE Jianxin. Effect of Natural Aging on the Artificial Aging Behavior of a New Al-Zn-Mg-Cu Alloy. Acta Metall Sin, 2026, 62(2): 383-396.

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Abstract

Al-Zn-Mg-Cu alloys are widely used to prepare aerospace lightweight structures owing to their excellent specific strength and damage tolerance. Their performance depends mainly on the high-density nanoprecipitates formed during artificial aging. However, natural aging after solution quenching changes the evolution path of the precipitates, affecting the subsequent artificial aging process. Currently, there is still considerable controversy regarding the impact of natural aging on the peak strength of these alloys after artificial aging. Therefore, this study investigated the contradictory effects of natural aging on the peak-aged strength of Al-Zn-Mg-Cu alloys after artificial aging. Using a newly developed ultrahigh-strength aluminum alloy, namely Al-9.8Zn-2.23Mg-1.38Cu-0.11Cr-0.1Zr (mass fraction, %), the effects of natural aging on precipitate evolution, solute element distribution, and mechanical properties in the peak-aged state were systematically explored. The results showed that natural aging accelerated the response of the material to subsequent artificial aging. The peak strengths after 0, 1, 7, and 30 d of natural aging and artificial aging were (708 ± 4), (685 ± 3), (712 ± 1), and (722 ± 1) MPa, respectively, exhibiting a trend of initial decrease followed by an increase. This behavior was attributed to the formation of Guinier-Preston I (GPI) zones (1.1-1.7 nm in diameter) during short-term natural aging (1 d), which partially dissolved during artificial aging. This reduced the number density of subsequently formed GPI zones, Guinier-Preston II (GPII) zones, and η′ phases and promoted their coarsening. In contrast, prolonged natural aging time increased the proportion of GPI zones, with sizes exceeding the critical nucleation threshold at artificial aging temperatures, facilitating the formation of finer and more dispersed precipitates during subsequent peak aging. Further, this led to a gradual increase in the proportion of GPII zones and decrease in the proportion of the η′ phase. Compared to the peak-aged sample naturally aged for 1 d, the sample naturally aged for 30 d exhibited an approximately 20% increase in the precipitate number density. In addition, the compositional gradient within precipitates of similar size became less pronounced, with significantly reduced maximum concentrations of Zn, Mg, and Cu.

Key words: Al-Zn-Mg-Cu alloy natural aging tensile property precipitate

Received: 27 June 2025

ZTFLH:

TG11

Fund: National Key Research and Development Program of China(2023YFB3710501);National Natural Science Foundation of China(52401002);Fundamental Research Funds for the Central Universities(FRF-BD-25-007);China Postdoctoral Science Foundation(2024M760200)

Corresponding Authors: ZHANG Zhihao, professor, Tel: (010)62332253, E-mail: zhangzhihao@ustb.edu.cn

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	JIANG Lei
	ZHOU Taiwentao
	ZHANG Xinbiao
	XIAO Xingyu
	ZHANG Zhihao
	XIE Jianxin

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https://www.ams.org.cn/EN/10.11900/0412.1961.2025.00184 OR https://www.ams.org.cn/EN/Y2026/V62/I2/383

Fig.1 HADDF-STEM analyses of the precipitates of the new aluminum alloy after different natural aging time
(a-c) high-angle annular dark field (HADDF)-STEM images of the precipitates after natural aging for 1 d (a), 7 d (b), and 30 d (c) (d-f) fast Fourier transform (FFT) after natural aging for 1 d (d), 7 d (e), and 30 d (f) corresponding to the rectangle areas in Figs.1a-c (Arrows in Fig.1f indicate weak diffraction spots) (g-i) atomic-level morphologies of the precipitates after natural aging for 1 d (g), 7 d (h), and 30 d (i)

Fig.2 Scattering vector modulus (q) versus scattering intensity relationship diagrams of the new aluminum alloy after different natural aging time obtained by small angle X-ray scattering (SAXS)

Fig.3 Hardnesses of the new aluminum alloy after different natural aging time followed by artificial aging at 120 ^oC for different time (a) and engineering stress-strain curves under artificial peak aging (b) (The samples with natural aging of 0, 1, 7, and 30 d following with artificial aging are named NA0, NA1, NA7, and NA30, respectively)

Fig.4 HADDF-STEM images of the small-angle grain boundaries of the new aluminum alloy after different natural aging time under artificial peak aging in samples NA0 (a), NA1 (b), NA7 (c), and NA30 (d); and HADDF-STEM image of grain boundary and corresponding EDS elemental mappings in NA30 sample (e)

Fig.5 TEM images of the intragranular precipitates of the new aluminum alloy after different natural aging time under artificial peak aging in samples NA0 (a), NA1 (b), NA7 (c), and NA30 (d); and TEM image of intragranular precipitates and corresponding EDS elemental mappings in NA30 sample (e)

Fig.6 Intragranular precipitate size statistics of the new aluminum alloy after different natural aging time under artificial peak aging in samples NA0 (a), NA1 (b), NA7 (c), and NA30 (d)

Fig.7 HADDF-STEM images of the intragranular precipitates of the new aluminum alloy after different natural aging time under artificial peak aging in samples NA0 (a), NA1 (b), NA7 (c), and NA30 (d); and corresponding FFT of rectangle areas in Figs.7a-d for GPII zone (e), η′ phase (f), GPI zone (g), and η phase (h), respectively (Arrows in Figs.7e, f, and h indicate weak diffraction spots)

Fig.8 Precipitate type statistics of the new aluminum alloy after different natural aging time under artificial peak aging in samples NA0 (a), NA1 (b), NA7 (c), and NA30 (d)

Fig.9 3D-APT analyses of the distributions of precipitates and solutes such as Zn, Mg, and Cu after different natural aging time under artificial peak aging in samples NA1 (a) and NA30 (b)

Fig.10 Proxigram analyses of typical precipitates after different natural aging time under artificial peak aging in samples NA1 and NA30
(a) typical GP zone in sample NA1 (b) typical GP zone in sample NA30
(c) typical η′ phase in sample NA1 (d) typical η′ phase in sample NA30

Table 1 Maximum contents of elements Zn, Mg, and Cu in the GP zone and η′ phase after different natural aging time under artificial peak aging in samples NA1 and NA30

Fig.11 Variations of precipitate free energy (ΔG^*) with precipitate radius (r) (r^*—critical nucleation size)

Fig.12 Schematics of the variations in the types and morphologies of precipitates under natural aging (a-d) and peak artificial aging (e-h) conditions
(a, e) NA0 (b, f) NA1 (c, g) NA7 (d, h) NA30

Table 2 Calculations of precipitation strengthening effects of the new aluminum alloys after different natural aging treatments

[1]	Hirsch J, Al-Samman T. Superior light metals by texture engineering: Optimized aluminum and magnesium alloys for automotive applications [J]. Acta Mater., 2013, 61: 818 doi: 10.1016/j.actamat.2012.10.044
[2]	Jiang L, Zhang Z H, Fu H D, et al. Corrosion behavior and mechanism of Al-Zn-Mg-Cu alloy based on the characterization of the secondary phases [J]. Mater. Charact., 2022, 189: 111974 doi: 10.1016/j.matchar.2022.111974
[3]	Dursun T, Soutis C. Recent developments in advanced aircraft aluminium alloys [J]. Mater. Des., 2014, 56: 862 doi: 10.1016/j.matdes.2013.12.002
[4]	Sun W W, Zhu Y M, Marceau R, et al. Precipitation strengthening of aluminium alloys by room-temperature cyclic plasticity [J]. Science, 2019, 363: 972 doi: 10.1126/science.aav7086
[5]	Jiang L, Zhang Z H, Hu H, et al. A rapid and effective method for alloy materials design via sample data transfer machine learning [J]. npj Comput. Mater., 2023, 9: 26 doi: 10.1038/s41524-023-00979-9
[6]	Deng Z C, He H, Liu K, et al. The influence of natural aging on the precipitation behavior of the low-alloy content Al-Zn-Mg aluminum alloys during subsequent artificial aging and related mechanisms [J]. Mater. Sci. Eng., 2024, A891: 145954
[7]	Lee S H, Jung J G, Baik S I, et al. Precipitation strengthening in naturally aged Al-Zn-Mg-Cu alloy [J]. Mater. Sci. Eng., 2021, A803: 140719
[8]	Zhang P, Shi K K, Bian J J, et al. Solute cluster evolution during deformation and high strain hardening capability in naturally aged Al-Zn-Mg alloy [J]. Acta Mater., 2021, 207: 116682 doi: 10.1016/j.actamat.2021.116682
[9]	Liu J Z, Hu R, Zheng J L, et al. Formation of solute nanostructures in an Al-Zn-Mg alloy during long-term natural aging [J]. J. Alloys Compd., 2020, 821: 153572 doi: 10.1016/j.jallcom.2019.153572
[10]	Francis M F, Curtin W A. Microalloying for the controllable delay of precipitate formation in metal alloys [J]. Acta Mater., 2016, 106: 117 doi: 10.1016/j.actamat.2016.01.014
[11]	Yang Z, Banhart J. Natural and artificial ageing in aluminium alloys—The role of excess vacancies [J]. Acta Mater., 2021, 215: 117014 doi: 10.1016/j.actamat.2021.117014
[12]	Wan L, Deng Y L, Ye L Y, et al. The natural ageing effect on pre-ageing kinetics of Al-Zn-Mg alloy [J]. J. Alloys Compd., 2019, 776: 469 doi: 10.1016/j.jallcom.2018.10.338
[13]	Ma P P, Liu C H, Chen Q Y, et al. Natural-ageing-enhanced precipitation near grain boundaries in high-strength aluminum alloy [J]. J. Mater. Sci. Technol., 2020, 46: 107 doi: 10.1016/j.jmst.2019.11.035
[14]	Liu S D, Li C B, Han S Q, et al. Effect of natural aging on quench-induced inhomogeneity of microstructure and hardness in high strength 7055 aluminum alloy [J]. J. Alloys Compd., 2015, 625: 34 doi: 10.1016/j.jallcom.2014.10.195
[15]	Kim Y Y, Rosenthal D F T, Shin D, et al. Effects of Sn addition on precipitation of a pre-naturally aged Al-Zn-Mg alloy during artificial aging [J]. Mater. Charact., 2024, 207: 113537 doi: 10.1016/j.matchar.2023.113537
[16]	Liu S D, Zhang M H, Li Q, et al. Effect of quenching rate on strengthening behavior of an Al-Zn-Mg-Cu alloy during natural ageing [J]. Mater. Sci. Eng., 2020, A793: 139900
[17]	Liu Y Q, Wang M, Liu X D, et al. The effect of combination of pre-ageing and regression heat treatment on the natural aging behavior in Al-Zn-Mg-Cu alloys correlated with precipitate dissolving ratio [J]. J. Mater. Res. Technol., 2024, 31: 2972 doi: 10.1016/j.jmrt.2024.07.018
[18]	Zhao J G, Liu Z Y, Bai S, et al. Effects of natural aging on the formation and strengthening effect of G.P. zones in a retrogression and re-aged Al-Zn-Mg-Cu alloy [J]. J. Alloys Compd., 2020, 829: 154469 doi: 10.1016/j.jallcom.2020.154469
[19]	Zhang D, Jiang H C, Cui Z J, et al. Synchronous improvement of mechanical properties and stress corrosion resistance by stress-aging coupled with natural aging pre-treatment in an Al-Zn-Mg alloy with high recrystallization fraction [J]. J. Mater. Sci. Technol., 2022, 121: 40 doi: 10.1016/j.jmst.2021.11.068
[20]	Waterloo G, Hansen V, Gjønnes J, et al. Effect of predeformation and preaging at room temperature in Al-Zn-Mg-(Cu,Zr) alloys [J]. Mater. Sci. Eng., 2001, A303: 226
[21]	Zou Y, Cao L F, Wu X D, et al. Synergetic effect of natural ageing and pre-stretching on the ageing behavior in Tʹ/ηʹ phase-strengthened Al-Zn-Mg-Cu alloys [J]. J. Mater. Sci. Technol., 2023, 146: 240 doi: 10.1016/j.jmst.2022.10.074
[22]	Österreicher J A, Kirov G, Gerstl S S A, et al. Stabilization of 7xxx aluminium alloys [J]. J. Alloys Compd., 2018, 740: 167 doi: 10.1016/j.jallcom.2018.01.003
[23]	Liu C H, Lai Y X, Chen J H, et al. Natural-aging-induced reversal of the precipitation pathways in an Al-Mg-Si alloy [J]. Scr. Mater., 2016, 115: 150 doi: 10.1016/j.scriptamat.2015.12.027
[24]	Tai C L, Tai P J, Hsiao T J, et al. Effect of natural ageing on subsequent artificial ageing of AA7075 aluminum alloy [J]. Metals, 2022, 12: 1766 doi: 10.3390/met12101766
[25]	Jiang L, Wang C S, Fu H D, et al. Discovery of aluminum alloys with ultra-strength and high-toughness via a property-oriented design strategy [J]. J. Mater. Sci. Technol., 2022, 98: 33 doi: 10.1016/j.jmst.2021.05.011
[26]	Jiang L, Zhang X B, Zhou T W T, et al. Discovery of ultra-high strength aluminum alloys with high damage tolerance via interpretable chain-based machine learning [J]. Mater. Des., 2025, 256: 114289 doi: 10.1016/j.matdes.2025.114289
[27]	Jiang L, Fu H D, Zhang Z H, et al. Synchronously enhancing the strength, toughness, and stress corrosion resistance of high-end aluminum alloys via interpretable machine learning [J]. Acta Mater., 2024, 270: 119873 doi: 10.1016/j.actamat.2024.119873
[28]	Chung T F, Yang Y L, Huang B M, et al. Transmission electron microscopy investigation of separated nucleation and in-situ nucleation in AA7050 aluminium alloy [J]. Acta Mater., 2018, 149: 377 doi: 10.1016/j.actamat.2018.02.045
[29]	Marlaud T, Deschamps A, Bley F, et al. Evolution of precipitate microstructures during the retrogression and re-ageing heat treatment of an Al-Zn-Mg-Cu alloy [J]. Acta Mater., 2010, 58: 4814 doi: 10.1016/j.actamat.2010.05.017
[30]	Perez M, Dumont M, Acevedo-Reyes D. Implementation of classical nucleation and growth theories for precipitation [J]. Acta Mater., 2008, 56: 2119 doi: 10.1016/j.actamat.2007.12.050
[31]	Grong Ø, Shercliff H R. Microstructural modelling in metals processing [J]. Prog. Mater. Sci., 2002, 47: 163 doi: 10.1016/S0079-6425(00)00004-9
[32]	Yang Q, Wang Z L, Xiao X Y, et al. CALPHAD-assisted composition and processing design of high-strength and high-conductivity copper alloy [J]. Mater. Sci. Eng., 2023, A881: 145432
[33]	Wang X Z, Zhao D D, Xu Y J, et al. Modelling the spatial evolution of excess vacancies and its influence on age hardening behaviors in multicomponent aluminium alloys [J]. Acta Mater., 2024, 264: 119552 doi: 10.1016/j.actamat.2023.119552
[34]	Zhao H, De Geuser F, da Silva A K, et al. Segregation assisted grain boundary precipitation in a model Al-Zn-Mg-Cu alloy [J]. Acta Mater., 2018, 156: 318 doi: 10.1016/j.actamat.2018.07.003
[35]	Sha G, Cerezo A. Early-stage precipitation in Al-Zn-Mg-Cu alloy (7050) [J]. Acta Mater., 2004, 52: 4503 doi: 10.1016/j.actamat.2004.06.025
[36]	Jiang L, Fu H D, Wang C S, et al. Enhanced mechanical and electrical properties of a Cu-Ni-Si alloy by thermo-mechanical processing [J]. Metall. Mater. Trans., 2020, 51A: 331
[37]	Jiang L, Han Z L, Zhang X B, et al. Investigation of secondary phases evolution and mechanical properties of ultra-high strength aluminum alloy driven by Cu element [J]. Mater. Sci. Eng., 2025, A933: 148285
[38]	Ma K K, Wen H M, Hu T, et al. Mechanical behavior and strengthening mechanisms in ultrafine grain precipitation-strengthened aluminum alloy [J]. Acta Mater., 2014, 62: 141 doi: 10.1016/j.actamat.2013.09.042
[39]	Seidman D N, Marquis E A, Dunand D C. Precipitation strengthening at ambient and elevated temperatures of heat-treatable Al(Sc) alloys [J]. Acta Mater., 2002, 50: 4021 doi: 10.1016/S1359-6454(02)00201-X
[40]	Pardoen T, Dumont D, Deschamps A, et al. Grain boundary versus transgranular ductile failure [J]. J. Mech. Phys. Solids, 2003, 51: 637 doi: 10.1016/S0022-5096(02)00102-3

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