SKM 2023 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 25: Development of Computational Methods: Crystal Structure and Properties
MM 25.2: Vortrag
Mittwoch, 29. März 2023, 10:30–10:45, SCH A 251
Corrosion evolution in Mg-based alloys: the role of precipitates studied by synchrotron X-ray nanotomography — •Tatiana Akhmetshina1, Robin E. Schäublin1, Andrea M. Rich1, Nicholas W. Phillips2, and Jörg F. Löffler1 — 1Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, Switzerland — 2Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
Magnesium alloys are very promising candidates for light-weight and bioresorbable medical applications. However, being an active metal, magnesium is susceptible to localized corrosion caused by precipitates or solute elements. In this work, we compare the corrosion behaviour of lean Mg-Ca (X0), developed in our laboratory, with the well-known Mg-Y-Nd-Zr (WE43) alloy that is currently deployed as biomedical material. X0 alloys (0.2-0.6 wt.% Ca) offer a combination of high strength and high ductility and can be considered a safe substitute for WE43 in bioresorbable implants. Using the 3D ptychography technique at the cSAXS beamline of the Swiss Light Source, we monitored the corrosion evolution in X0 and WE43. Both exhibit very different precipitates, which can be distinguished by their electron density in X-ray imaging. We found that the rare-earth-rich precipitates in WE43 tend to remain in the corrosion layer, whereas the Ca-rich ones in X0 predominantly dissolve without any pitting effect. The appearance of the corrosion product and the related chemical composition were also quite different. These findings of in-vitro corrosion can help to better understand the in-vivo degradation of Mg-based biomedical devices.