Al-Cu-Li alloys present an excellent strength-to-weight ratio, rendering them well-suited for aeronautic applications. The mechanical strength of the alloy is enhanced through an optimal combination of precipitates, including $\theta'$ and $T1$[1]. One effective method for enhancing mechanical strength involves employing High-Pressure Torsion (HPT), a form of severe plastic deformation, which induces ultra-fine grain crystal structures in materials [2].  

The main aim of the study is to systematically investigate the precipitation behavior of an Al-Cu-Li alloy subjected to HPT. For investigation of the evolving phases after HPT, we employed small-angle X-ray scattering (SAXS), powder diffraction, transmission electron microscopy (TEM), and scanning electron microscopy (SEM). Despite the presence of pores in the initial powder sample, as evidenced by SEM images, leading to challenges in formulating volume fractions due to scattering effects, our investigation successfully identified the formation of T2 precipitates during the HPT process, which were microscopically confirmed in TEM images. Significantly, a robust agreement in size distribution was observed between TEM and the results obtained through SAXS. The experimental data is compared with numerical results of an established numerical Kampmann-Wagner precipitation model. 

Acknowledgement

This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No 101001567).

References

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2. Kurmanaeva, L, Ivanisenko, Y., Markmann, J, Ku¨bel, C, Chuvilin, A, Doyle, S, Valiev, R. & Fecht, H.-J. Grain refinement and mechanical properties in ultrafine grained Pd and Pd–Ag alloys produced by HPT. Materials Science and Engineering: A 527, 1776–1783 (2010).