Influence of temperature on creep behavior, mechanical properties and microstructural evolution of an Al-Cu-Li alloy during creep age forming

Abstract

The effect of temperature in range of 155–175 °C on the creep behavior, microstructural evolution, and precipitation of an Al-Cu-Li alloy was experimentally investigated during creep ageing deformation under 180 MPa for 20 h. Increasing temperature resulted in a noteworthy change in creep ageing behaviour, including a variation in creep curves, an improvement in creep rate during early creep ageing, and an increased creep strain. Tensile tests indicate that the specimen aged at higher temperature reached peak strength within a shorter time. Transmission electron microscopy (TEM) was employed to explore the effect of temperature on the microstructural evolution of the AA2198 during creep ageing deformation. Many larger dislocations and even tangled dislocation structures were observed in the sample aged at higher temperature. The number of T₁ precipitates increased at higher ageing temperature at the same ageing time. Based on the analysed results, a new mechanism, considering the combined effects of the formation of larger dislocation structures induced by higher temperature and diffusion of solute atoms towards these larger or tangled dislocations, was proposed to explain the effect of temperature on microstructural evolution and creep behaviour.

Keywords

Al-Cu-Li alloys / creep age forming / mechanical properties / microstructure / precipitation

References

[1] JeshvaghaniR A, EmamiM, ShahverdiH R, HadaviS M M. Effects of time and temperature on the creep forming of 7075 aluminum alloy: Springback and mechanical properties [J]. Materials Science and Engineering A, 2011, 528: 8795-8799

[2] ZhanL-H, LinJ-G, DeanT A. A review of the development of creep age forming: Experimentation, modelling and applications [J]. International Journal of Machine Tools and Manufacture, 2011, 51: 1-17

[3] ZhanL-H, LinJ-G, DeanT A, HuangM-H. Experimental studies and constitutive modelling of the hardening of aluminium alloy 7055 under creep age forming conditions [J]. International Journal of Mechanical Sciences, 2011, 53: 595-605

[4] RiojaR J, LiuJ. The evolution of Al-Li base products for aerospace and space applications [J]. Metallurgical and Materials Transactions A, 2012, 43: 3325-3337

[5] WarnerT. Recently-developed aluminium solutions for aerospace applications [J]. Materials Science Forum, 2006, 519–521: 1271-1278

[6] KumarK S, BrownS A, PickensJ R. Microstructural evolution during aging of an Al-Cu-Li-Ag-Mg-Zr alloy [J]. Acta Materialia, 1996, 44: 1899-1915

[7] GayleF W, HeubaumF H, PichensJ R. Structure and properties during aging of an ultra-high strength Al-Cu-Li-Ag-Mg alloy [J]. Scripta Metallurgica et Materialia, 1990, 24: 79-84

[8] NobleB, ThompsonG E. T₁ (Al₂CuLi) precipitation in aluminium-copper-lithium alloys [J]. Metal Science Journal, 2013, 6: 167-174

[9] GanleB M, ZhuA W, CsontosA A, StarkeE AJr. The role of plastic deformation on the competitive microstructural evolution and mechanical properties of a novel Al-Li-Cu-X alloy [J]. Journal of Light Metals, 2001, 1: 1-14

[10] DecreusB, DeschampsA, GeuserF D, DonnadieuP, SigliC, WeylandM. The influence of Cu/Li ratio on precipitation in Al-Cu-Li-X alloys [J]. Acta Materialia, 2013, 61: 2207-2218

[11] DonnadieuP, ShaoY, GeuserF D, BottonG A, LazarS, CheynetM, BoissieuM D, DeschampsA. Atomic structure of T₁ precipitates in Al-Li-Cu alloys revisited with HAADF-STEM imaging and small-angle X-ray scattering [J]. Acta Materialia, 2011, 59(2): 462-472

[12] NieJ F, MuddleB C. On the form of the age-hardening response in high strength aluminium alloys [J]. Materials Science and Engineering A, 2001, 319–321: 448-451

[13] DeschampsA, DecreusB, GeuserF D, DorinT, WeylangM. The influence of precipitation on plastic deformation of Al-Cu-Li alloys [J]. Acta Materialia, 2013, 61: 4010-4021

[14] CsontosA A, StarkeE A. The effect of inhomogeneous plastic deformation on the ductility and fracture behavior of age hardenable aluminum alloys [J]. International Journal of Plasticity, 2005, 21(6): 1097-1118

[15] RingerS P, MuddleB C, PolmearI J. Effects of cold work on precipitation in Al-Cu-Mg-(Ag) and Al-Cu-Li-(Mg-Ag) alloys [J]. Metallurgical and Materials Transactions A, 1995, 26: 1659-1671

[16] Araullo-PetersV, GaultB, GeuserF D, DeschampsA, CairneyJ M. Microstructural evolution during ageing of Al-Cu-Li-X alloys [J]. Acta Materialia, 2014, 66: 199-208

[17] DorinT, GeuserF D, LefebvreW, SigliC, DeschampsA. Strengthening mechanisms of T₁ precipitates and their influence on the plasticity of an Al-Cu-Li alloy [J]. Materials Science and Engineering A, 2014, 605: 119-126

[18] LyuF, LiY, ShiZ-S, HuangX, ZengY, LinJ-G. Stress and temperature dependence of stress relaxation ageing behaviour of an Al-Zn-Mg alloy [J]. Materials Science and Engineering A, 2020, 773: 138859

[19] ZhangS-F, ZengW-D, YangW-H, ShiC-L, WangH-J. Ageing response of a Al-Cu-Li 2198 alloy [J]. Materials and Design, 2014, 63368-374

[20] ZhuX-H, LinY C, WuQ, JiangY-Q. Effects of aging on precipitation behavior and mechanical properties of a tensile deformed Al-Cu alloy [J]. Journal of Alloys and Compounds, 2020, 843: 155975

[21] ZouY, CaoL-F, WuX-D, WangY-C, SunX, SongH, CouperM J. Effect of ageing temperature on microstructure, mechanical property and corrosion behavior of aluminum alloy 7085 [J]. Journal of Alloys and Compounds, 2020, 823153792

[22] ZhouC, ZhanL-H, ShenR-L, ZhaoX, YuH-L, HuangM-H, LiH, YangY-L, HuL-B, LiuD-B, HuZ-G. Creep behavior and mechanical properties of Al-Li-S4 alloy at different aging temperatures [J]. Journal of Central South University, 2020, 27(4): 1168-1175

[23] TsivoulasD, RobsonJ D. Heterogeneous Zr solute segregation and Al₃Zr dispersoid distributions in Al-Cu-Li alloys [J]. Acta Materialia, 2015, 9373-86

[24] LiuC-H, MalladiS K, XuQ, ChenJ-H, TichelaarF D, ZhugeX-D, ZandbergenH W. In-situ STEM imaging of growth and phase change of individual CuAlX precipitates in Al alloy [J]. Scientific Reports, 2017, 72184

[25] ZhangW, SuiM L, ZhouY Z, LiD X. Evolution of microstructures in materials induced by electropulsing [J]. Micron, 2003, 34(3–5): 189-198