1. State Key Laboratory of High-efficiency Utilization of Coal and Green Chemical Engineering, College of Chemistry and Chemical Engineering, Ningxia University, Yinchuan 750021, China 2. School of Materials Science and Engineering, Central South University, Changsha 410083, China 3. Department of Chemistry, Zhejiang University, Hangzhou 310058, China
Cite this article:
Chao CAI,Yang LI,Jinfeng LI,Zhao ZHANG,Jianqing ZHANG. Correlation Between Ageing Precipitation, Potential and Intergranular Corrosion of 2A97 Al-Li Alloy Sheet. Acta Metall Sin, 2019, 55(8): 958-966.
The microstructures and open circuit potential (OCP) of 2A97 Al-Li alloy sheets with different ageing and their corrosion features in intergranular corrosion (IGC) medium were investigated. As the extension of ageing time, T1 (Al2CuLi) phases are precipitated, the alloy potential is decreased, which is accompanied with the following corrosion mode evolution: pitting, IGC (including local IGC and general IGC) and pitting again. Meanwhile, with ageing progress, the IGC depth is increased firstly and then decreased. Compared to T6 ageing, T8 ageing accelerates the precipitation of T1 phases, the potential therefore decreases more quickly. After a certain ageing, the lower the potential, the smaller the IGC degree, and the greater the pitting degree. A correlation between OCP and corrosion mode was proposed, which may be used to compare the IGC sensitivity of Al-Li alloy with different tempers.
Fund: National Natural Science Foundation of China (No.51741107)(No.51741107);Major Innovation Projects for Building First-Class Universities in China's Western Region(No.ZKZD17003);National First-Class Discipline Construction Project of Ningxia(No.NXYLXK2017A04)
Fig.1 Typical sectional corrosion morphologies of 2A97 Al-Li alloy with T6 ageing after corrosion test for 2 h (a), 4 h (b), 58 h (c) and 120 h (d)
Time / h
Dominating corrosion mode
Max. IGC depth / μm
Max. pitting depth / μm
0
Pitting
-
120
2
Local IGC
140
-
4
General IGC
238
-
6
General IGC
221
-
11.5
Local IGC with pitting
179
101
22
Local IGC with pitting
134
135
36
Pitting with local IGC
101
192
45
Pitting with local IGC
72
163
58
Pitting with local IGC
82
151
68
Pitting with slight IGC
-
199
72
Pitting with slight IGC
-
227
98
Pitting with slight IGC
-
167
120
Pitting with slight IGC
-
181
Table 1 Corrosion type and maximum corrosion depth of 2A97 Al-Li alloy with T6 ageing after corrosion test for different time
Fig.2 Typical sectional corrosion morphologies of 2A97 Al-Li alloy with T8 ageing after corrosion test for 2 h (a), 4 h (b), 36 h (c) and 120 h (d)
Time / h
Dominating corrosion mode
Max. IGC depth / μm
Max. pitting depth / μm
0
Pitting
-
125
1
Pitting and local IGC
60
122
2
Pitting and local IGC
90
120
4
Pitting with local IGC
115
125
10
Pitting
-
98
22
Pitting
-
107
28
Pitting
-
100
36
Pitting
-
107
48
Pitting
-
127
60
Pitting
-
110
72
Pitting
-
140
120
Pitting
-
100
Table 2 Corrosion type and maximum corrosion depth of 2A97 Al-Li alloy with T8 ageing after corrosion test for different time
Fig.3 Polarization curves of 2A97 Al-Li alloy sheet with T6 ageing for different time
Fig.4 Open circuit potential of 2A97 Al-Li alloy sheet with T6 and T8 ageing for different time in 3.5%NaCl solution
Fig.5 TEM images of 2A97 Al-Li alloy with T6 ageing for 4 h (a, b), 12 h (c, d) and 60 h (e, f)(a, c, e) <100>Al direction (b, d, f) <112>Al direction
Fig.6 TEM images of 2A97 Al-Li alloy with T8 ageing for 4 h (a, b), 16 h (c, d) and 40 h (e, f)(a, c, e) <100>Al direction (b, d, f) <112>Al direction
Fig.7 Phenomenological corrosion diagram relating OCP evolution to corrosion mode
[1]
Rioja R J, Liu J. The evolution of Al-Li base products for aerospace and space applications [J]. Metall. Mater. Trans., 2012, 43A: 3325
[2]
Zhang X F, Li G A, Lu Z, et al. Effect of preaged stretch after quenched on the properties and microstructure of a naturally aged Al-Li alloy [J]. Acta Metall. Sin., 2016, 52: 1497
Zhang X L, Zhang L, Wu G H, et al. Influences of Mg content on the microstructures and mechanical properties of cast Al-2Li-2Cu-0.2Zr alloy [J]. J. Mater. Sci., 2019, 54: 791
[4]
Yang Y, Zhou K, Li G J. Surface gradient microstructural characteristics and evolution mechanism of 2195 aluminum lithium alloy induced by laser shock peening [J]. Opt. Laser. Technol., 2019, 109: 1
[5]
Wei X Y, Zheng Z Q, She L J, et al. Microalloying roles of Mg and Zn additions in 2099 Al-Li alloy [J]. Rare Met. Mater. Eng., 2010, 39: 1583
Luo X F, Zheng Z Q, Zhong J F, et al. Effects of Mg, Ag and Zn multi-alloying on aging behavior of new Al-Cu-lialloy [J]. Chin. J. Nonferrous Met., 2013, 23: 1833
Li J F, Birbilis N, Liu D Y, et al. Intergranular corrosion of Zn-free and Zn-microalloyed Al-xCu-y Lialloys [J]. Corros. Sci., 2016, 105: 44
[8]
Liu D Y, Li J F, Ma Y L, et al. A closer look at the role of Zn in the microstructure and corrosion of an Al-Cu-Li alloy [J]. Corros. Sci., 145: 220
[9]
Liu F J, Fu L, Zhang W Y. Interface structure and mechanical pro-perties of friction stir welding joint of 2099-T83/2060-T8 dissimilar Al-Li alloys [J]. Acta Metall. Sin., 2015, 51: 281
Liu W C, Feng S, Li Z Q, et al. Effect of rolling strain on microstructure and tensile properties of dual-phase Mg-8Li-3Al-2Zn-0.5Y alloy [J]. J. Mater. Sci. Technol., 2018, 34: 2256
[11]
Zhou X, Liu Q, Liu R R, et al. Characterization of microstructure and mechanical properties of Mg-8Li-3Al-1Y alloy subjected to different rolling processes [J]. Met. Mater. Int., 2018, 24: 1359
[12]
Donatus U, Berbel L O, Costa I. Qualitative use of potentiodynamic polarization and anodic hydrogen evolution in the assessment of corrosion susceptibility in AA2198-T851 Al-Cu-Li alloy [J]. Mater. Corros., 2018, 69: 1375
[13]
Liu Q, Zhu R H, Liu D Y, et al. Correlation between artificial aging and intergranular corrosion sensitivity of a new Al-Cu-Li alloy sheet [J]. Mater. Corros., 2017, 68: 65
[14]
Huang J L, Li J F, Liu D Y, et al. Correlation of intergranular corrosion behaviour with microstructure in Al-Cu-Li alloy [J]. Corros. Sci., 2018, 139: 215
[15]
Proton V, Alexis J, Andrieu E, et al. The influence of artificial ageing on the corrosion behaviour of a 2050 aluminium-copper-lithium alloy [J]. Corros. Sci., 2014, 80: 494
[16]
Cai C, Li J F, Wang H, et al. Dependence of intergranular corrosion sensitivity of Al-Li alloys on aging stage [J]. Rare Met. Mater. Eng., 2015, 44: 2523
Ning A L, Liu Z Y, Feng C, et al. Study of microstructure, electrical conductivity and stress corrosion resistance of Al-Zn-Mg-Cu alloys [J]. Trans. Mater. Heat Treat., 2008, 29(2): 108
Xia L, Zhan X H, Yu H S. Morphology and formation mechanism of equiaxed grains along the fusion boundary in Al-Li alloy weld seam [J]. Mater. Res. Exp., 2018, 5: 116523
[21]
Li J F, Ye Z H, Liu D Y, et al. Influence of pre-deformation on aging precipitation behavior of three Al-Cu-Li alloys [J]. Acta Metall. Sin. (Engl. Lett.), 2017, 30: 133
[22]
Gable B M, Zhu A W, Csontos A A, et al. The role of plastic deformation on the competitive microstructural evolution and mechanical properties of a novel Al-Li-Cu-X alloy [J]. J. Light Met., 2001, 1: 1
[23]
Sun J, Wang C, Song J L, et al. Multi-functional application of oil-infused slippery Al surface: From anti-icing to corrosion resistance [J]. J. Mater. Sci., 2018, 53: 16099
[24]
Li J F, Zheng Z Q, Li S C, et al. Simulation study on function mechanism of some precipitates in localized corrosion of Al alloy [J]. Corros. Sci., 2007, 49: 2436
[25]
Li J F, Li C X, Peng Z W, et al. Corrosion mechanism associated with T1 and T2 precipitates of Al-Cu-Li alloys in NaCl solution [J]. J. Alloys Compd., 2008, 460: 688
