M.D. Martín-Alonso¹, F. Benn^2,3, A. Kopp², M. Majkut⁴, J. Villanova⁴, J.M. Molina-Aldareguia¹, F. Sket¹

¹IMDEA Materials Institute, Getafe (Madrid), Spain, ²Meotec GmbH & Co.,Aachen, Germany, ³Queen's University Belfast, Belfast, United Kingdom ⁴European Synchrotron Radiation Facility (ESRF) (Grenoble), France.

* mariadolores.martin@imdea.org

Porous Mg scaffolds manufactured by laser powder bed fusion (LPBF) are promising structures for bone regeneration as they allow tissue ingrowth and permit body fluid transportation. Moreover, Mg implants can be fully re-absorbed by the human body, and the mechanical properties are similar to those of bone, which prevents stress shielding effects [1]. Applying Mg scaffolds as a bone regeneration system requires detailed knowledge of the degradation behaviour and the load-bearing capability during degradation. These two properties are investigated to obtain suitable mechanical strength and controlled degradation, the latter allowing for handled and sustainable bone ingrowth.

LPBF-manufactured open porous cubic scaffolds of 10x10x10 mm3 of WE43 alloy with different lattice structures (BCC, FCC, TPMS), and an average strut diameter of 500 µm were surface modified by plasma electrolytic oxidation (PEO) to improve corrosion resistance and biocompatibility [2]. The mechanical properties and fracture mechanisms were ascertained by in situ synchrotron X-ray microtomography compression tests in as built scaffolds and after immersion in simulated body fluid for different time periods (i.e. 7, 14, 21 days). Digital Image and Volume Correlation (DIC and DVC) techniques were then applied to obtain localized deformations and the strain fields along the structure to fully understand the influence of corrosion in mechanical failure.

The multi-resolution capability of synchrotron X-ray micro- and nano-tomography allowed to follow the evolution of the deformation process, including the PEO rupture due to load and corrosion, as well as the corrosion products distribution, and to understand the precise mechanical and degradation behaviour.

References

[1] M. Li, F. Benn, T. Derra, N. Kröger, M. Zinser, R. Smeets, J. Molina-Aldareguia, J. Llorca Materials Science and Engineering, 2021, 119, 111623.

[2] A. Kopp, T. Derra, M. Müther, L. Jauer, J. H. SchleifenbauM, M. Voshage, & N. Kröger Acta biomaterialia, 2019, 98, 23–35.