<p>Magnesium alloys as medical implant materials necessitate a lower and adjustable corrosion rate for clinical applications. The microstructure and corrosion behavior of AZ31Mn-<i>x</i>Er (<i>x</i>=0.1, 0.5, 1.2) alloys were systematically investigated using optical microscopy (OM), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS), combined with Tafel polarization and electrochemical impedance spectroscopy (EIS) analyses. The findings showed that the alloying element Er refined the grain structure during solidification by increasing the nucleation rate and forming a secondary phase of Al<sub>3</sub>Er with Al. The Er and Mg in the matrix co-oxidize to form a dense MgO/Er<sub>2</sub>O<sub>3</sub> composite oxide, preventing the formation of loose magnesium hydroxide/basic magnesium carbonate. The trace alloying element Mn interacts with impurities Fe in the magnesium matrix to form an AlFeMn second phase, reducing micro-galvanic corrosion driving force. Electrochemical testing in a 3.5% NaCl solution demonstrated a marked reduction in corrosion rate from 10.46 mm/a (AZ31Mn alloy) to 0.44 mm/a (AZ31Mn-1.2Er alloy). This research offers a reference for searching for corrosion-resistant magnesium alloy and degradable medical magnesium alloy materials.</p>

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Effects of Er on microstructure and corrosion resistance of degradable Mg-Al-Zn-Mn magnesium alloy

  • Wei Ma,
  • Zheng-qing Ma,
  • Bai-hua Chen

摘要

Magnesium alloys as medical implant materials necessitate a lower and adjustable corrosion rate for clinical applications. The microstructure and corrosion behavior of AZ31Mn-xEr (x=0.1, 0.5, 1.2) alloys were systematically investigated using optical microscopy (OM), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS), combined with Tafel polarization and electrochemical impedance spectroscopy (EIS) analyses. The findings showed that the alloying element Er refined the grain structure during solidification by increasing the nucleation rate and forming a secondary phase of Al3Er with Al. The Er and Mg in the matrix co-oxidize to form a dense MgO/Er2O3 composite oxide, preventing the formation of loose magnesium hydroxide/basic magnesium carbonate. The trace alloying element Mn interacts with impurities Fe in the magnesium matrix to form an AlFeMn second phase, reducing micro-galvanic corrosion driving force. Electrochemical testing in a 3.5% NaCl solution demonstrated a marked reduction in corrosion rate from 10.46 mm/a (AZ31Mn alloy) to 0.44 mm/a (AZ31Mn-1.2Er alloy). This research offers a reference for searching for corrosion-resistant magnesium alloy and degradable medical magnesium alloy materials.