Researchers improve corrosion resistance in AM bioabsorbable alloys
Researchers from IMDEA Materials Institute and Universidad Politécnica de Madrid, both in Spain, and German institutions Meotec, Aachen, and Institute of Surface Science, Geesthacht, have published a paper in Surface and Coatings Technologies which demonstrates how manufacturing and surface treatment affect corrosion in extrusion and additively manufactured bioabsorbable metals.
‘Influence of manufacturing route and surface modification on the corrosion behavior of WE43 Mg and Zn1Mg bioabsorbable metallic alloys’ focuses on the electrochemical behaviour of the named magnesium and zinc alloys when produced by Material Extrusion (MEX) or Laser Beam Powder Bed Fusion (PBF-LB) Additive Manufacturing techniques, both with and without subsequent plasma electrolytic oxidation (PEO) surface treatment.
![SEM images of the degraded PEO treated surfaces in the PDP tests. A) corresponds to extruded WE43MEO, B) to PBF-LB WE43MEO, C) to extruded Zn1Mg, D) to PBF-LB Zn1Mg (Courtesy M Bohner, M Bermúdez, A Godec Matjaz, et al., ‘Influence of manufacturing route and surface modification on the corrosion behavior of WE43 Mg and Zn1Mg bioabsorbable metallic alloys’ (Surface and Coatings Technology 475 [2025]) 129205)](http://www.metal-am.com/wp-content/uploads/sites/4/2025/07/Untitled-design-46.png)
The extruded WE43 showed a corrosion rate of 3.42 ± 0.10 mm/year, while the counterpart produced via PBF-LB showed an increased corrosion rate of 11.85 ± 0.14 mm/year. This increase was explained via yttrium oxide particles found in the PBF-LB material that decrease the protective effect of the corrosion layer, and hence reduce corrosion resistance.
For the Zn1Mg, the extruded sample had a corrosion rate of 0.98 ± 0.41 mm/year, whereas the PBF-LB sample also showed a higher corrosion rate of 2.70 ± 0.09 mm/year. This result was explained by a higher volume fraction of second phase eutectic structure in the PBF-LB samples, which increased the microgalvanic corrosion between Zn grains and MgZn structures in the eutectic phase.
The extruded samples showed thicker PEO oxide layer in both the WE43 and Zn1Mg materials than the samples produced via PBF-LB. In all cases, the surface treatments were found to improve corrosion resistance.
The researchers have stated that these findings underscore the impact of evaluating the influence of different manufacturing methods and PEO surface treatments on the corrosion resistance and durability of these biomedical alloys.
The full paper is available here.
