Effect of the Content and Morphology of β‐Compounds and Precipitation on the Corrosion Behavior of Biodegradable Magnesium Alloys

• Published in: Advanced engineering materials Vol. 23; no. 1
• Main Authors: Gui, Zhenzhen, Kang, Zhixin, Zhou, Yan, Zhang, Jianhui
• Format: Journal Article
• Language: English
• Published: 01.01.2021
• Subjects: biodegradable magnesium; corrosion behavior; microgalvanic corrosion; precipitation; β‐compounds
• ISSN: 1438-1656; 1527-2648
• DOI: 10.1002/adem.202000752

Microstructure analyses, immersion tests, and electrochemical measurements are performed to investigate the corrosion behavior of Mg–1.59Nd–2.91–Zn–0.05Zr–0.35Mn (NZKM) alloy under three different conditions (as‐cast, heat‐treated, and as‐extruded) in Hanks’ solution. The results indicate that the corrosion rates of the three types of NZKM alloys are all lower than 0.5 mm year−1. The primary driving force of the NZKM alloys’ corrosion is the microgalvanic coupling between α‐Mg and β‐compounds/precipitates in Hanks’ solution during the corrosion process. The lowest corrosion rates can be attributed to a low content of β‐compounds and less precipitation, a necklace‐type appearance, and discontinuous distribution of the β‐compounds in the heat‐treated NZKM alloy. The clustered precipitation that occurs within the as‐extruded NZKM exacerbates the corrosion process due to the formation of clustered microgalvanic couple groups. These results indicate that the content of β‐compounds and precipitation of the NZKM alloys, as well as their appearances and distributions, should be controlled to allow for further application as biodegradable materials. Corrosion behavior of as‐cast, heat‐treated, and as‐extruded Mg–1.59Nd–2.91Zn–0.05Zr–0.35Mn (NZKM) alloy in Hanks’ solution is studied. The primary driving force of the corrosion process of the NZKM alloys is the formation of a microgalvanic couple between α‐Mg and β‐compounds/precipitates. Differences in the corrosion behavior are due to the content, morphologies, and distribution of the β‐compounds/precipitates.