Abstract
The influence of solidification cooling rate on the microstructure, particularly Fe-rich particles, in a Mg-0.1Ca (wt%) alloy is studied, as well as the corresponding effect on the corrosion resistance. It is revealed that a slow cooling rate (<5 K s−1) is required for Mg–Ca lean alloys to achieve high corrosion resistance, with corrosion rates <0.2 mm y−1 (in 3.5 wt% NaCl solution). With a low cooling rate, Fe-rich particles with a few hundred nanometers in size are found but largely wrapped by CaMgSi intermetallics at the micrometer scale introduced by Ca addition. Therefore, Fe is sequestered from the matrix, which suppresses micro-galvanic corrosion and cathodic hydrogen evolution kinetics, contributing to the improved corrosion resistance by three orders of magnitude in comparison to that of a high-purity Mg (~20 ppm Fe). However, high cooling rates (like 260 K s−1) result in obviously decreased size of CaMgSi, leaving more Fe-rich particles incompletely wrapped or even fully isolated, which promote cathodic hydrogen-evolution kinetics and intensify micro-galvanic corrosion. Thus, the Mg-0.1Ca alloy shows decreased corrosion resistance when the cooling rate increases. This work demonstrates the significance of Ca micro-alloying and solidification control for developing corrosion-resistant Mg by eliminating the detrimental effect associated with parts-per-million-level Fe impurity.
Data availability
The datasets generated and/or analyzed during the current study are available from the corresponding author on reasonable request.
References
Esmaily, M. et al. Fundamentals and advances in magnesium alloy corrosion. Prog. Mater. Sci. 89, 92–193 (2017).
Liu, M., Guo, Y., Wang, J. & Yergin, M. Corrosion avoidance in lightweight materials for automotive applications. npj Mater. Degrad. 2, 24 (2018).
Yuan, Y. et al. Research advances of magnesium and magnesium alloys globally in 2024. J. Magnes. Alloys 13, 4689–4732 (2025).
Lee, J. U. et al. Chemical and mechanical properties of stainless, environment-friendly, and nonflammable Mg alloys (SEN alloys): a review. J. Magnes. Alloys 12, 841–872 (2024).
Deng, B. et al. Effect of Zn addition on the stress corrosion cracking of as-cast BCC Mg-11Li based alloys. Corros. Sci. 227, 111707 (2024).
Tong, Z. et al. Improving the corrosion resistance of an ultra-lightweight BCC Mg-Li-Zn alloy via controlling the microstructure by heat treatment. J. Magnes. Alloys 13, 2325–2342 (2025).
Lin, H. et al. Effect of electrochemical cathodic hydrogen charging on the surface film of an ultralight Mg–Li–Zn alloy. Int. J. Hydrog. Energy 159, 150628 (2025).
Tian, J. et al. Laser-assisted wire-arc additive manufacturing of Mg-Al-Ce-Mn-Ca alloy with enhanced corrosion resistance. Corros. Sci. 261, 113608 (2026).
Matsubara, H., Ichige, Y., Fujita, K., Nishiyama, H. & Hodouchi, K. Effect of impurity Fe on corrosion behavior of AM50 and AM60 magnesium alloys. Corros. Sci. 66, 203–210 (2013).
Hofstetter, J. et al. Influence of trace impurities on the in vitro and in vivo degradation of biodegradable Mg–5Zn–0.3Ca alloys. Acta Biomater. 23, 347–353 (2015).
Höche, D. et al. The effect of iron re-deposition on the corrosion of impurity-containing magnesium. Phys. Chem. Chem. Phys. 18, 1279–1291 (2016).
Liu, M. et al. Calculated phase diagrams and the corrosion of die-cast Mg–Al alloys. Corros. Sci. 51, 602–619 (2009).
Woo, S. K., Suh, B.-C., Kim, H. S. & Yim, C. D. Effect of processing history on corrosion behaviours of high purity Mg. Corros. Sci. 184, 109357 (2021).
Chen, Z., Duan, X., Wei, W., Wang, S. & Ni, B.-J. Recent advances in transition metal-based electrocatalysts for alkaline hydrogen evolution. J. Mater. Chem. A 7, 14971–15005 (2019).
Cao, F. et al. Corrosion of ultra-high-purity Mg in 3.5% NaCl solution saturated with Mg(OH)2. Corros. Sci. 75, 78–99 (2013).
Atrens, A. et al. Review of Mg alloy corrosion rates. J. Magnes. Alloys 8, 989–998 (2020).
Song, G. L. & Atrens, A. Corrosion Mechanisms of Magnesium Alloys. Adv. Eng. Mater. 1, 11–33 (1999).
Lamaka, S. V. et al. Comprehensive screening of Mg corrosion inhibitors. Corros. Sci. 128, 224–240 (2017).
Yang, L. et al. Effect of traces of silicon on the formation of Fe-rich particles in pure magnesium and the corrosion susceptibility of magnesium. J. Alloys Compd. 619, 396–400 (2015).
Baek, S.-M., Kim, J.-K., Min, D.-W. & Park, S. S. Remarkably slow corrosion rate of high-purity Mg microalloyed with 0.05wt%. Sc. J. Magnes. Alloys 11, 991–997 (2023).
Deng, M. et al. Approaching stainless magnesium by Ca micro-alloying. Mater. Horiz. 8, 589–596 (2021).
Deng, M., Höche, D., Lamaka, S. V., Snihirova, D. & Zheludkevich, M. L. Mg-Ca binary alloys as anodes for primary Mg-air batteries. J. Power Sources 396, 109–118 (2018).
Deng, M. et al. Ca/In micro alloying as a novel strategy to simultaneously enhance power and energy density of primary Mg-air batteries from anode aspect. J. Power Sources 472, 228528 (2020).
Bornapour, M., Celikin, M., Cerruti, M. & Pekguleryuz, M. Magnesium implant alloy with low levels of strontium and calcium: The third element effect and phase selection improve bio-corrosion resistance and mechanical performance. Mater. Sci. Eng.: C. 35, 267–282 (2014).
Li, G. et al. Effects of Ca and Sn on microstructure and mechanical properties of Mg-4Zn Alloy. Spec. Cast. Nonferrous Alloys 42, 1263–1269 (2022).
Jeong, Y. S. & Kim, W. J. Enhancement of mechanical properties and corrosion resistance of Mg–Ca alloys through microstructural refinement by indirect extrusion. Corros. Sci. 82, 392–403 (2014).
Bahari-Sambran, F., Carreño, F., Cepeda-Jiménez, C. M. & Orozco-Caballero, A. Predicting grain size-dependent superplastic properties in friction stir processed ZK30 magnesium alloy with machine learning methods. J. Magnes. Alloys 12, 1931–1943 (2024).
Liu, K. et al. Effects of deformation temperatures on microstructures, aging behaviors and mechanical properties of Mg-Gd-Er-Zr alloys fabricated by hard-plate rolling. J. Magnes. Alloys 12, 2345–2359 (2024).
Pan, H. et al. Ultra-fine grain size and exceptionally high strength in dilute Mg–Ca alloys achieved by conventional one-step extrusion. Mater. Lett. 237, 65–68 (2019).
Deng, M. et al. Micro-alloyed Mg-Ca: corrosion susceptibility to heating history and a plain problem-solving approach. J. Magnes. Alloys 11, 1193–1205 (2023).
Woo, S. K., Suh, B.-C., Kim, H. S. & Yim, C. D. Effect of Al addition on corrosion behavior of high-purity Mg in terms of processing history. J. Magnes. Alloys 11, 851–868 (2023).
Jin, Y. et al. Deteriorated corrosion performance of micro-alloyed Mg-Zn alloy after heat treatment and mechanical processing. J. Mater. Sci. Technol. 92, 214–224 (2021).
Jixue, Z. et al. Effect of cooling rate on the solidified microstructure of Mg-Gd-Y-Zr alloy. Rare Met. Mater. Eng. 39, 1899–1902 (2010).
Guo, E., Wang, L., Feng, Y., Wang, L. & Chen, Y. Effect of cooling rate on the microstructure and solidification parameters of Mg–3Al–3Nd alloy. J. Therm. Anal. Calorim. 135, 2001–2008 (2018).
Cai, H. et al. Effects of cooling rate on the microstructure and properties of magnesium alloy-a review. J. Magnes. Alloys 12, 3094–3114 (2024).
Jin, Q. Q. et al. The role of melt cooling rate on the interface between 18R and Mg matrix in Mg97Zn1Y2 alloys. J. Magnes. Alloys 11, 2883–2890 (2023).
Khan, M. I., Mostafa, A. O., Aljarrah, M., Essadiqi, E. & Medraj, M. Influence of cooling rate on microsegregation behavior of magnesium alloys. J. Mater. 2014, 1–18 (2014).
Liu, Y. et al. Comparative, real-time in situ monitoring of galvanic corrosion in Mg-Mg2Ca and Mg-MgZn2 couples in Hank’s solution. Corros. Sci. 161, 108185 (2019).
Wang, C. et al. High rate oxygen reduction reaction during corrosion of ultra-high-purity magnesium. npj Mater. Degrad. 4, 42 (2020).
Deng, M. et al. Clarifying the decisive factors for utilization efficiency of Mg anodes for primary aqueous batteries. J. Power Sources 441, 227201 (2019).
Yang, Y. et al. The effects of a corrosion product film on the corrosion behavior of Mg-Al alloy with micro-alloying of yttrium in a chloride solution. Corros. Commun. 11, 12–22 (2023).
Wang, L. et al. Non-stationarity in electrochemical impedance measurement of Mg-based materials in aqueous media. Electrochim. Acta 468, 143140 (2023).
Wang, L. et al. Insight into physical interpretation of high frequency time constant in electrochemical impedance spectra of Mg. Corros. Sci. 187, 109501 (2021).
Wang, L. et al. Revealing physical interpretation of time constants in electrochemical impedance spectra of Mg via Tribo-EIS measurements. Electrochim. Acta 404, 139582 (2022).
Jin, Y. et al. Time-sequential corrosion behaviour observation of micro-alloyed Mg-0.5Zn-0.2Ca alloy via a quasi-in situ approach. Corros. Sci. 158, 108096 (2019).
Ben-Hamu, G., Eliezer, D. & Shin, K. S. The role of Si and Ca on new wrought Mg–Zn–Mn based alloy. Mater. Sci. Eng.: A 447, 35–43 (2007).
Bahmani, A., Arthanari, S. & Shin, K. S. Corrosion behavior of Mg–Mn–Ca alloy: influences of Al, Sn and Zn. J. Magnes. Alloys 7, 38–46 (2019).
Yang, H. et al. Clarifying the roles of grain boundary and grain orientation on the corrosion and discharge processes of α-Mg based Mg-Li alloys for primary Mg-air batteries. J. Mater. Sci. Technol. 62, 128–138 (2021).
Kim, H. S., Kim, G. H., Kim, H. & Kim, W. J. Enhanced corrosion resistance of high strength Mg–3Al–1Zn alloy sheets with ultrafine grains in a phosphate-buffered saline solution. Corros. Sci. 74, 139–148 (2013).
Ralston, K. D., Birbilis, N. & Davies, C. H. J. Revealing the relationship between grain size and corrosion rate of metals. Scr. Mater. 63, 1201–1204 (2010).
Zhou, P. et al. Grain refinement promotes the formation of phosphate conversion coating on Mg alloy AZ91D with high corrosion resistance and low electrical contact resistance. Corros. Commun. 1, 47–57 (2021).
Cao, F. et al. Influence of hot rolling on the corrosion behavior of several Mg–X alloys. Corros. Sci. 90, 176–191 (2015).
Yin, S. et al. Influence of specific second phases on corrosion behaviors of Mg-Zn-Gd-Zr alloys. Corros. Sci. 166, 108419 (2020).
Chu, P.-W. & Marquis, E. A. Linking the microstructure of a heat-treated WE43 Mg alloy with its corrosion behavior. Corros. Sci. 101, 94–104 (2015).
Candan, S., Celik, M. & Candan, E. Effectiveness of Ti-micro alloying in relation to cooling rate on corrosion of AZ91 Mg alloy. J. Alloys Compd. 672, 197–203 (2016).
Cao, F., Shi, Z., Song, G.-L., Liu, M. & Atrens, A. Corrosion behaviour in salt spray and in 3.5% NaCl solution saturated with Mg(OH)2 of as-cast and solution heat-treated binary Mg–X alloys: X=Mn, Sn, Ca, Zn, Al, Zr, Si, Sr. Corros. Sci. 76, 60–97 (2013).
Yang, L. et al. Effect of iron content on the corrosion of pure magnesium: critical factor for iron tolerance limit. Corros. Sci. 139, 421–429 (2018).
Deng, M. et al. Corrosion and discharge properties of Ca/Ge micro-alloyed Mg anodes for primary aqueous Mg batteries. Corros. Sci. 177, 108958 (2020).
Liu, R. L., Scully, J. R., Williams, G. & Birbilis, N. Reducing the corrosion rate of magnesium via microalloying additions of group 14 and 15 elements. Electrochim. Acta 260, 184–195 (2018).
Shi, Z. & Atrens, A. An innovative specimen configuration for the study of Mg corrosion. Corros. Sci. 53, 226–246 (2011).
Ci, W. et al. Achieving ultra-high corrosion-resistant Mg-Zn-Sc alloys by forming Sc-assisted protective corrosion product film. J. Mater. Sci. Technol. 181, 138–151 (2024).
Yin, M. et al. Self-generating construction of applicable corrosion-resistant surface structure of magnesium alloy. Corros. Sci. 184, 109378 (2021).
Chen, X., Venezuela, J. & Dargusch, M. The high corrosion-resistance of ultra-high purity Mg–Ge alloy and its discharge performance as anode for Mg–air battery. Electrochim. Acta 448, 142127 (2023).
Acknowledgements
This work was financially supported by the National Key Research and Development Program of China (2024YFB3408900 and 2023YFF0716204), National Natural Science Foundation of China (52401042), High-level Talent Introduction Program of Hebei Province (2022HBQZYCXY005 and 2024HBQZYCXY003) and Science and Technology Project of Hebei Education Department (No. BJ2025130).
Author information
Authors and Affiliations
Contributions
Y.Q. carried out the investigation and wrote the original draft of the manuscript. M.D. conceived the study and supervised the project. J.R. contributed to the methodology and performed validation. B.W., Y.X., and S.J. contributed to the methodology, with S.J. also responsible for funding acquisition. H.W. contributed to manuscript review and editing, and funding acquisition. All authors reviewed and approved the final manuscript.
Corresponding authors
Ethics declarations
Competing interests
The authors declare no competing interests.
Additional information
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Rights and permissions
Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc-nd/4.0/.
About this article
Cite this article
Qi, Y., Deng, M., Rong, J. et al. Achieving a corrosion-resistant Mg-Ca lean alloy by solidification control to sequester parts-per-million-level Fe impurity. npj Mater Degrad (2026). https://doi.org/10.1038/s41529-026-00755-2
Received:
Accepted:
Published:
DOI: https://doi.org/10.1038/s41529-026-00755-2
