The Influence of Mg and Ag on the Precipitation Kinetics and the Formation of the T₁ Phase in Al-Cu-Li Alloys

Abstract:

Al-Cu-Li alloys are extensively used for aerospace applications. The main hardening phase is the T₁ phase that precipitates as thin platelets on {111}_Al planes. To facilitate its nucleation, different minor alloying elements are added and dislocations are introduced by cold deformation before the ageing treatment. The impact of these additions in combination with the presence of dislocations on precipitate nucleation and growth needs a deeper understanding. In this work, we investigated the precipitation kinetics of the T₁ phase in alloys containing a common content of Cu and Li and different contents of minor solutes (Mg, Ag) where these elements are present either together or independently. A general overview on the precipitation kinetics was achieved by in-situ small-angle X-ray scattering and hardness measurements. The evaluation of precipitation kinetics reveals that magnesium plays an important role during precipitation by enhancing nucleation kinetics. Additionally, a smaller yet measureable effect of Ag, both in the presence and absence of Mg has been evidenced.

• Periodical: Materials Science Forum (Volumes 794-796)
• Pages: 945-950
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.794-796.945
• Online since: June 2014
• Authors: Eva Gumbmann*, Frederic de Geuser, Williams Lefebvre, Christophe Sigli, Alexis Deschamps
• Keywords: Al-Cu-Li Alloy, Minor Alloying Elements, Precipitation Kinetics, SAXS

References

[1] T. Warner, Recently-Developed Aluminium Solutions for Aerospace Applications, Mater. Sci. Forum, Bd. 519–521, S. 1271–1278, (2006).

DOI: 10.4028/www.scientific.net/msf.519-521.1271

[2] C. Giummarra, B. Thomas, und R. J. Rioja, New aluminium lithium alloys for aerospace applications, Proc. Light Met. Technol. Conf. (2007).

[3] R. J. Rioja und J. Liu, The Evolution of Al-Li Base Products for Aerospace and Space Applications, Metall. Mater. Trans. A, Bd. 43, Nr. 9, S. 3325–3337, Sep. (2012).

DOI: 10.1007/s11661-012-1155-z

[4] T. Warner, J. C. Ehrström, B. Chenal, und F. Eberl, Alcan's Innovative Aluminium-Based Solutions for Aerospace Applications, Light metal age, S. 18 – 21, (2009).

[5] J. C. Huang und A. J. Ardell, On the Crystal Structure and Stability of the T1 Precipitates in Aged Al-Li-Cu Alloys, (1987).

[6] S. Van Smaalen, A. Meetsma, J. L. De Boer, und P. M. Bronsveld, Refinement of the crystal structure of hexagonal Al2CuLi, J. Solid State Chem., Bd. 85, Nr. 2, S. 293–298, Apr. (1990).

DOI: 10.1016/s0022-4596(05)80086-6

[7] P. Donnadieu, Y. Shao, F. De Geuser, G. A. Botton, S. Lazar, M. Cheynet, M. de Boissieu, und A. Deschamps, Atomic structure of T1 precipitates in Al–Li–Cu alloys revisited with HAADF-STEM imaging and small-angle X-ray scattering, Acta Mater., Bd. 59, Nr. 2, S. 462–472, Jan. (2011).

DOI: 10.1016/j.actamat.2010.09.044

[8] C. Dwyer, M. Weyland, L. Y. Chang, und B. C. Muddle, Combined electron beam imaging and ab initio modeling of T1 precipitates in Al–Li–Cu alloys, Appl. Phys. Lett., Bd. 98, Nr. 20, S. 201909–201909–3, Mai (2011).

DOI: 10.1063/1.3590171

[9] W. A. Cassada, G. J. Shiflet, und E. A. Starke, Mechanism of Al2CuLi (T 1) nucleation and growth, Metall. Trans. A, Bd. 22, Nr. 2, S. 287–297, Feb. (1991).

DOI: 10.1007/bf02656798

[10] W. A. Cassada, G. J. Shiflet, und E. A. Starke, The effect of plastic deformation on Al2CuLi (T 1) precipitation, Metall. Trans. A, Bd. 22, Nr. 2, S. 299–306, Feb. (1991).

DOI: 10.1007/bf02656799

[11] B. . Gable, A. . Zhu, A. . Csontos, und E. . Starke Jr., The role of plastic deformation on the competitive microstructural evolution and mechanical properties of a novel Al–Li–Cu–X alloy, J. Light Met., Bd. 1, Nr. 1, S. 1–14, Feb. (2001).

DOI: 10.1016/s1471-5317(00)00002-x

[12] G. Itoh, Q. Cui, und M. Kanno, Effects of a small addition of magnesium and silver on the precipitation of T1 phase in an Al-4%Cu-1. 1%Li-0. 2%Zr alloy, Mater. Sci. Eng. A, Bd. 211, Nr. 1–2, S. 128–137, Juni (1996).

DOI: 10.1016/0921-5093(95)10157-8

[13] R. Yoshimura, T. J. Konno, E. Abe, und K. Hiraga, Transmission electron microscopy study of the evolution of precipitates in aged Al–Li–Cu alloys: the θ' and T1 phases, Acta Mater., Bd. 51, Nr. 14, S. 4251–4266, Aug. (2003).

DOI: 10.1016/s1359-6454(03)00253-2

[14] B. Decreus, A. Deschamps, F. De Geuser, P. Donnadieu, C. Sigli, und M. Weyland, The influence of Cu/Li ratio on precipitation in Al–Cu–Li–x alloys, Acta Mater.

DOI: 10.1016/j.actamat.2012.12.041

[15] S. C. Wang und M. J. Starink, Precipitates and intermetallic phases in precipitation hardening Al–Cu–Mg–(Li) based alloys, Int. Mater. Rev. Vol. 50 Number 4 August 2005 Pp 193-21523.

DOI: 10.1179/174328005x14357

[16] R. Yoshimura, T. J. Konno, E. Abe, und K. Hiraga, Transmission electron microscopy study of the early stage of precipitates in aged Al–Li–Cu alloys, Acta Mater., Bd. 51, Nr. 10, S. 2891–2903, Juni (2003).

DOI: 10.1016/s1359-6454(03)00104-6

[17] B. -P. Huang und Z. -Q. Zheng, Independent and combined roles of trace Mg and Ag additions in properties precipitation process and precipitation kinetics of Al–Cu–Li–(Mg)–(Ag)–Zr–Ti alloys, Acta Mater., Bd. 46, Nr. 12, S. 4381–4393, Juli (1998).

DOI: 10.1016/s1359-6454(98)00079-2

[18] D. L. Gilmore und E. A. S. Jr, Trace element effects on precipitation processes and mechanical properties in an Al-Cu-Li alloy, Metall. Mater. Trans. A, Bd. 28, Nr. 7, S. 1399–1415, Juli (1997).

DOI: 10.1007/s11661-997-0203-6

[19] M. Murayama und K. Hono, Role of Ag and Mg on precipitation of T1 phase in an Al-Cu-Li-Mg-Ag alloy, Scr. Mater., Bd. 44, Nr. 4, S. 701–706, März (2001).

DOI: 10.1016/s1359-6462(00)00651-5

[20] B. Gault, F. de Geuser, L. Bourgeois, B. M. Gabble, S. P. Ringer, und B. C. Muddle, Atom probe tomography and transmission electron microscopy characterisation of precipitation in an Al–Cu–Li–Mg–Ag alloy, Ultramicroscopy, Bd. 111, Nr. 6, S. 683–689, Mai (2011).

DOI: 10.1016/j.ultramic.2010.12.004

[21] Z. Q. Zheng, S. Q. Liang, H. Xu, C. Y. Tan, und D. F. Yun, Effect of 0. 5% silver on the age hardening behaviour of an Al-Li-Cu-Mg-Zr alloy, J. Mater. Sci. Lett., Bd. 12, Nr. 14, S. 1111–1113, Jan. (1993).

DOI: 10.1007/bf00420537

[22] F. De Geuser, F. Bley, und A. Deschamps, A new method for evaluating the size of plate-like precipitates by small-angle scattering, J. Appl. Crystallogr., Bd. 45, Nr. 6, Nov. (2012).

DOI: 10.1107/s0021889812039891

[23] F. De Geuser und A. Deschamps, Precipitate characterisation in metallic systems by small-angle X-ray or neutron scattering, Comptes Rendus Phys., Bd. 13, Nr. 3, S. 246–256, avril (2012).

DOI: 10.1016/j.crhy.2011.12.008

[24] T. Dorin, A. Deschamps, F. De Geuser, W. Lefebvre, und C. Sigli, Quantitative description of the T1 formation kinetics in an Al–Cu–Li alloy using differential scanning calorimetry, small-angle X-ray scattering and transmission electron microscopy, Philos. Mag., Bd. 0, Nr. 0, S. 1–19, 0.

DOI: 10.1080/14786435.2013.878047

[25] L. Bourgeois, C. Dwyer, M. Weyland, J. -F. Nie, und B. C. Muddle, Structure and energetics of the coherent interface between the θ' precipitate phase and aluminium in Al–Cu, Acta Mater., Bd. 59, Nr. 18, S. 7043–7050, Okt. (2011).

DOI: 10.1016/j.actamat.2011.07.059

[26] H. Fujita und C. Lu, An Electron Microscope study of G. P. Zones and θ'-Phase in Al-1. 6 at%Cu Crystals, Mater. Trans. JIM, Bd. 33, Nr. 10, S. 892–896, (1992).

DOI: 10.2320/matertrans1989.33.892