The S-Phase Formation in a High-Purity Al-Cu-Mg Alloy Monitored by Truncation during Heating-Up

Abstract:

We present a novel attempt to combine in-situ and ex-situ measurements -- here exemplary for aluminum alloys. For this research we have chosen an Al-1.7Cu-1.3Mg (at.\%) alloy, which has been cast from high purity elements (5N5 Al, 4N Cu and 4N Mg). DSC (differential scanning calorimetry) serves as a basic method, which is employed to determine different precipitation states towards the final S-phase formation: before the formation starts, at the maximum of the exothermal peak, and after the end of the exothermal reaction. By an abrupt truncation of the heating ramp (5 K/min), i.e. cooling quickly to room temperature, the current sample state is frozen-in for a defined temperature. After truncation all samples have been measured without further preparation by X-ray diffraction (XRD), positron annihilation lifetime spectroscopy (PALS). By this treatment we could correlate exactly different sample states, which is impossible by conventional experiments, i.e. heating to a defined temperature and holding for a certain time. This attempt opens new possibilities to investigate defined and comparable sample states by methods, which require extensive sample preparation, like TEM or 3DAP, and in-situ methods like DSC or XRD / EXAFS / SAXS at synchrotron beam lines.

• Periodical: Solid State Phenomena (Volume 374)
• Pages: 87-102
• DOI: https://doi.org/10.4028/p-iC99pF
• Online since: July 2025
• Authors: Torsten E.M. Staab*, Dominik Boras, Sebastian Breitfelder, Timo Strobl
• Keywords: Al-Cu-Mg Alloys, Aluminium Alloys, Annealing Curves, DSC, Heating Rates, Positron Annihilation Lifetime Spectroscopy (PALS), S-Phase, XRD

References

[1] R. Ivanov, A. Deschamps, and F. De Geuser. A combined characterization of clusters in naturally aged Al-Cu-(Li, Mg) alloys using small-angle neutron and X-ray scattering and atom probe tomography. J. Appl. Cryst., 50:1725–1734, 2017.

DOI: 10.1107/s1600576717014443

[2] F. Lotter, D. Petschke F. De Geuser, M. Elsayed, G. Sextl, and T.E.M. Staab. In situ natural ageing of Al-Cu-(Mg) alloys: The effect of In and Sn on the very early stages of decomposition. Scripta Materialia, 168:104–107, 2019.

DOI: 10.1016/j.scriptamat.2019.04.031

[3] Danny Petschke, Frank Lotter, Elischa Bläss, and Torsten EM Staab. Time-resolved X-ray absorption spectroscopy on al-cu alloys from solute copper to stable precipitates. Journal of Applied Crystallography, 51(5):1339–1351, 2018.

DOI: 10.1107/s1600576718011214

[4] L. Kovarik and M.J. Mills. Structural relationship between one-dimensional crystals of Guinier– Preston–Bagaryatsky zones in Al-Mg-Cu alloys. Scripta Materialia, 64:999–1002, 2011.

DOI: 10.1016/j.scriptamat.2011.01.033

[5] S.P. Ringer, K. Hono, I.J. Polmear, and T. Sakurai. Precipitation processes during the early stages of ageing in Al-Cu-Mg alloys. Appl. Surf. Sci., 94-95:253–260, 1996.

DOI: 10.1016/0169-4332(95)00383-5

[6] S.P. Ringer, K. Hono, T. Sakurai, and I.J. Polmear. Cluster hardening in an aged Al–Cu–Mg alloys. Scripta Mater., 36(5):517–521, 1997.

DOI: 10.1016/s1359-6462(96)00415-0

[7] S.P. Ringer, T. Sakurai, and I.J. Polmear. Origins of hardening in aged Al–Cu–Mg–(Ag) alloys. Acta Mater., 45(9):3721–3744, 1997.

DOI: 10.1016/s1359-6454(97)00039-6

[8] S.P. Ringer, S.K. Caraher, and I.J. Polmear. Response to comments on "cluster hardening in an aged Al–Cu–Mg alloys". Scripta Mater., 39(11):1559–1567, 1998.

DOI: 10.1016/s1359-6462(98)00364-9

[9] A.-M. Zahra, C.Y. Zahra, C. Alfonso, and A. Charai. Comments on "cluster hardening in an aged Al–Cu–Mg alloy". Scripta Mater., 39(11):1553–1558, 1998.

DOI: 10.1016/s1359-6462(98)00365-0

[10] S.C. Wang and M.J. Starink. Precipitates and intermetallic phases in precipitation hardening Al–Cu–Mg–(Li) based alloys. International Materials Reviews, 50(4):193–215, 2005.

DOI: 10.1179/174328005x14357

[11] Y. Nagai, M. Murayama, Z. Tang, T. Nonaka, K. Hono, and M. Hasegawa. Role of vacancy– solute complex in the initial rapid age hardening in an Al-Mg-Cu alloy. Acta materialia, 49(5):913–920, 2001.

DOI: 10.1016/s1359-6454(00)00348-7

[12] A. Guinier. La diffraction de rayon X aux tres petis angles: Application a l'etude de phenomenes ultramicroscopiques. Ann. Phys., 12:161–237, 1938.

DOI: 10.1051/anphys/193911120161

[13] G.D. Preston. The diffraction of X-rays by an age-hardening aluminum and copper alloys. Proc. Royal Soc., 167:526–538, 1938.

DOI: 10.1098/rspa.1938.0152

[14] G.D. Preston. The diffraction of X-rays by an age-hardening alloy of aluminum and copper: The structure of an intermediate phase. Phil. Mag., 26:855–871, 1938.

[15] Yu. A. Bagaryatsky. About the nature of natural ageing of Al alloys. Dokl. Akad. Nauk CCCP, Tom 87(3):559–562, 1952.

[16] Yu. A. Bagaryatsky. The mechanism of artificial ageing of Al–Cu–Mg alloys. Dokl. Akad. Nauk CCCP, Tom 87(3):397–401, 1952.

[17] A. Charai, T. Walther, C. Alfonso, A.-M. Zahra, and C.Y. Zahra. Coexistance of clusters, GPB zones, S"-, S'- and S-phases in an Al–0.9% Cu–1.4% Mg alloy. Acta Mater., 48:2751–2764, 2000.

DOI: 10.1016/s1359-6454(99)00422-x

[18] J.M. Robles Campillo, E. Ogando, and F. Plazaola. Positron lifetime calculation for the elements of the periodic table. Journal of Physics: Condensed Matter, 19(17):176222, 2007.

DOI: 10.1088/0953-8984/19/17/176222

[19] Peter Haasen. Physikalische Metallkunde. Springer-Verlag, 1994.

[20] Günter Gottstein. Materialwissenschaft und Werkstofftechnik: Physikalische Grundlagen. Springer-Verlag, 2014.

[21] Danny Petschke, Frank Lotter, and Torsten E.M. Staab. Revisiting the crystal structure of the equilibrium S (Al2CuMg) phase in Al–Cu–Mg alloys using X-ray absorption spectroscopy (XAFS). Materialia, 6:100341, 2019.

DOI: 10.1016/j.mtla.2019.100341

[22] Benjamin Milkereit, Lydia Giersberg, Olaf Kessler, and Christoph Schick. Isothermal timetemperature- precipitation diagram for an aluminum alloy 6005a by in situ DSC experiments. Materials, 7(4):2631–2649, 2014.

DOI: 10.3390/ma7042631

[23] Benjamin Milkereit, Olaf Kessler, and Christoph Schick. Precipitation and dissolution kinetics in metallic alloys with focus on aluminium alloys by calorimetry in a wide scanning rate range. In Fast scanning calorimetry, pages 723–773. Springer, 2016.

DOI: 10.1007/978-3-319-31329-0_22

[24] H. Perlitz and A. Westgren. Ark. för Kemi. Mineral. och Geol., 16B, 1943.

[25] Danny Petschke and Torsten E.M. Staab. DDRS4PALS: A software for the acquisition and simulation of lifetime spectra using the DRS4 evaluation board. SoftwareX, 10:100261, 2019.

DOI: 10.1016/j.softx.2019.100261

[26] Stefan Ritt. Design and performance of the 6 GHz waveform digitizing chip DRS4. In 2008 IEEE Nuclear Science Symposium Conference Record, pages 1512–1515. IEEE, 19.10.2008 - 25.10.2008.

DOI: 10.1109/nssmic.2008.4774700

[27] Software download for the DRS4 evaluation board, 2018.

[28] Danny Petschke. dpscience/DQuickLTFit: DQuickLTFit v4.2 (version 4.2), 2021.

[29] P. Kirkegaard and M. Eldrup. POSITRONFIT: A versatile program for analyzing positron lifetime spectra. Computer Phys.Commun., 3:240–255, 1972.

DOI: 10.1016/0010-4655(72)90070-7

[30] K. Levenberg. A method for the solution of certain non-linear problems in least squares. In Q. Appl. Math. 2, pages 164–168. 1963.

DOI: 10.1090/qam/10666

[31] M. Elsayed, A.M. Ibrahim, T.E.M. Staab, and R. Krause-Rehberg. A new perspective on the precipitation sequence in a high-purity Al-1:74 at.% Cu alloy by employing positron annihilation spectroscopy: Experiment and theory. J. Phys.: Condens. Matter, 33:435401, 2021.

DOI: 10.1088/1361-648x/ac17af

[32] S. Linderoth, H. Rajainmäki, and R.M. Nieminen. Defect recovery in aluminum irradiated with protons at 20 K. Phys. Rev., B35(11):5524–5528, 1987.

DOI: 10.1103/physrevb.35.5524

[33] M. Elsayed, T.E.M. Staab, J. Ĉiz􀀀ek, and R. Krause-Rehberg. Monovacancy-hydrogen interaction in pure aluminum: Experimental and ab-initio theoretical positron annihilation study. Acta Materialia, 248:118770, 2023.

DOI: 10.1016/j.actamat.2023.118770

[34] T.E.M. Staab, E. Zschech, and R. Krause-Rehberg. Positron lifetime measurements for the characterization of nano-structural changes in the age hardenable AlCuMg 2024 alloy. J. Mater. Sci., 35:4667–4672, 2000.

DOI: 10.1023/a:1004838619943