Researchers have reported that friction stir processing can alter the biodegradation behavior of the AZ41 magnesium alloy, a material of growing interest for biodegradable biomedical applications such as tissue engineering, orthopedic implants, and cardiovascular devices. The study, published in the Journal of Materials Science, examined how the alloy degrades in simulated body fluid, a key factor governing how such materials are expected to perform in vivo.
The team, led by Maryam Mehdizade, Ali Reza Eivani, Yashar Naghshin, Morteza Tayebi, and Amir Mostafaei, subjected AZ41 magnesium alloy to single-pass friction stir processing using different combinations of shoulder and pin sizes.
Microstructural characterization showed that the samples processed with a larger pin and a smaller shoulder exhibited more refined grains and a more uniform distribution of secondary phase particles.
Electrochemical testing in simulated body fluid revealed that the best-performing condition reached the highest polarization resistance measured in the study, 61.16 Ω cm², alongside the lowest reported corrosion rate of 394.8 mm/year. These values come from the authors’ electrochemical measurements and characterize the relative differences among the processed conditions rather than a clinical performance claim.
The corrosion that occurred proceeded through a combination of uniform and pitting mechanisms. Importantly, the researchers observed that grain refinement led to a reduction in pitting, suggesting that the microstructural changes introduced by friction stir processing directly shaped the degradation mode of the alloy.
Consistent with the electrochemical results, samples processed with the larger pin and smaller shoulder size showed lower mass gain and lower biodegradation rates compared with the other processed conditions.
The study also linked degradation behavior to the chemistry of the surrounding fluid. Samples with higher degradation rates and lower corrosion resistance exhibited higher Mg2+ release and increased pH. This connection means that the electrochemical and immersion measurements reinforced one another: the alloys that corroded fastest also changed the solution chemistry most strongly.
Overall, the findings indicate that tool geometry in friction stir processing is a practical lever for tuning the biodegradation behavior of AZ41 magnesium alloy in simulated body fluid. By selecting a larger pin with a smaller shoulder, the researchers achieved finer grains, a more uniform secondary phase distribution, reduced pitting, and the most favorable electrochemical and biodegradation metrics reported in the study. The work was conducted entirely in vitro using simulated body fluid, so the results describe laboratory degradation behavior and do not establish in vivo performance; the authors frame this biodegradation behavior as a key factor governing how the alloy might ultimately perform in biomedical settings.
Subject of Research: Biocorrosion and biomineralization behavior of friction stir processed AZ41 magnesium alloy in simulated body fluid
Article Title: Biocorrosion behavior and biomineralization of friction stir processed AZ41 Mg alloy
Article References: Mehdizade, M., Eivani, A. R., Naghshin, Y., Tayebi, M., & Mostafaei, A. (2026). Biocorrosion behavior and biomineralization of friction stir processed AZ41 Mg alloy. Journal of Materials Science, 61(41), 32003-32022. https://doi.org/10.1007/s10853-026-13652-5
Image Credits: AI Generated
DOI: 10.1007/s10853-026-13652-5
Keywords: AZ41 magnesium alloy, friction stir processing, biocorrosion, biomineralization, biodegradable metals, simulated body fluid, grain refinement, pitting corrosion, polarization resistance, biomedical implants, electrochemical testing, orthopedic implants
