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Microstructure analysis and corrosion behavior of biodegradable Mg–Ca implant alloys
Highlights ► Evaluation of corrosion mechanism and solidification behavior of Mg–xCa. ► Microstructure of Mg–xCa alloys were characterized by XRD, OM, SEM and EDS. ► Thermal analysis of alloys was carried out by computer aided cooling curve analysis. ► The addition of Ca content increase Mg2Ca lead to increasing corrosion rate.
Abstract The calcium content in binary Mg–xCa alloys affects the microstructure, corrosion and solidification behavior of the alloys. In this study, binary Mg–xCa alloys with various Ca contents from 0.5 to 10wt.% were produced by casting process. Microstructural evolutions were characterized by optical microscopy, X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy. Solidification behavior was assessed via two thermocouple thermal analysis method. The corrosion resistance was examined in vitro by potentiodynamic polarization and immersion test in Kokubo solution at room temperature. The results revealed that the grain size and dendrite cell size decreased significantly with rising Ca content, whilst the content of Mg2Ca intermetallic phase in grain boundaries increased with increasing Ca content. Potentiodynamic polarization tests in simulated body fluid (SBF) indicated that corrosion rates of Mg–xCa alloy increased significantly with rising Ca content. Immersion tests in Kokubo solution also showed that dissolution rate of Mg–xCa alloy increased with increasing Mg2Ca content which lead to an increase in pH value. It was observed that corrosion damage in specimens with lower Ca content was more moderate and uniform than higher Ca content. Thermal analysis results showed that the fraction of primary α-Mg at dendrite coherency point decreased with increasing Ca content but the liquid fraction f L increased causing the rise in eutectic Mg2Ca intermetallic phase in grain boundaries, thus increasing the corrosion rate. Our analyses showed that Mg–0.5Ca alloy is a promising alloy to be used as biodegradable implants.
Microstructure analysis and corrosion behavior of biodegradable Mg–Ca implant alloys
Highlights ► Evaluation of corrosion mechanism and solidification behavior of Mg–xCa. ► Microstructure of Mg–xCa alloys were characterized by XRD, OM, SEM and EDS. ► Thermal analysis of alloys was carried out by computer aided cooling curve analysis. ► The addition of Ca content increase Mg2Ca lead to increasing corrosion rate.
Abstract The calcium content in binary Mg–xCa alloys affects the microstructure, corrosion and solidification behavior of the alloys. In this study, binary Mg–xCa alloys with various Ca contents from 0.5 to 10wt.% were produced by casting process. Microstructural evolutions were characterized by optical microscopy, X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy. Solidification behavior was assessed via two thermocouple thermal analysis method. The corrosion resistance was examined in vitro by potentiodynamic polarization and immersion test in Kokubo solution at room temperature. The results revealed that the grain size and dendrite cell size decreased significantly with rising Ca content, whilst the content of Mg2Ca intermetallic phase in grain boundaries increased with increasing Ca content. Potentiodynamic polarization tests in simulated body fluid (SBF) indicated that corrosion rates of Mg–xCa alloy increased significantly with rising Ca content. Immersion tests in Kokubo solution also showed that dissolution rate of Mg–xCa alloy increased with increasing Mg2Ca content which lead to an increase in pH value. It was observed that corrosion damage in specimens with lower Ca content was more moderate and uniform than higher Ca content. Thermal analysis results showed that the fraction of primary α-Mg at dendrite coherency point decreased with increasing Ca content but the liquid fraction f L increased causing the rise in eutectic Mg2Ca intermetallic phase in grain boundaries, thus increasing the corrosion rate. Our analyses showed that Mg–0.5Ca alloy is a promising alloy to be used as biodegradable implants.
Microstructure analysis and corrosion behavior of biodegradable Mg–Ca implant alloys
Rad, Hamid Reza Bakhsheshi (author) / Idris, Mohd Hasbullah (author) / Kadir, Mohammed Rafiq Abdul (author) / Farahany, Saeed (author)
2011-01-01
10 pages
Article (Journal)
Electronic Resource
English
Microstructure analysis and corrosion behavior of biodegradable Mg-Ca implant alloys
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