Influence of chemical heterogeneity and microstructure on the corrosion resistance of biodegradable WE43 magnesium alloys
Influence of chemical heterogeneity and microstructure on the corrosion resistance of biodegradable WE43 magnesium alloys
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DOI：
10.1039/c9tb00388f
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发表时间：
2019-11-07
影响因子：
7
通讯作者：
Cai, Wenjun
中科院分区：
文献类型：
--
作者：
Mraied, Hesham;Wang, Wenbo;Cai, Wenjun
镁-钇-稀土元素合金如WE 43由于其生物相容性、与人骨相似的机械性能以及在体内完全降解的能力，是未来生物可吸收骨科植入材料的潜在候选材料。然而，WE 43镁合金在生理环境中的高腐蚀速率和随后的结构完整性损失限制了这些材料的广泛应用。在这项研究中，化学非均匀性和微观结构对两种不同的冶金状态的合金的耐腐蚀性的影响进行了研究：铸造（在传统的制备）和磁控溅射产生的沉积。采用动电位极化曲线和电化学阻抗谱研究了该材料在血库缓冲盐溶液中的腐蚀行为。结果发现，由于消除了Mg基体和沉淀物之间的微电偶耦合，沉积态合金的腐蚀电流密度比铸造合金降低了一个数量级以上。通过浸泡试验、X射线光电子能谱（XPS）和截面透射电镜（TEM）分析，探讨了两种合金腐蚀产物的微观结构和形成机理。
Magnesium-yttrium-rare earth element alloys such as WE43 are potential candidates for future bioabsorbable orthopedic implant materials due to their biocompatibility, mechanical properties similar to human bone, and the ability to completely degrade in vivo. Unfortunately, the high corrosion rate of WE43 Mg alloys in physiological environments and subsequent loss of structural integrity limit the wide applications of these materials. In this study, the effect of chemical heterogeneity and microstructure on the corrosion resistance of two alloys with different metallurgical states was investigated: cast (as in traditional preparation) and as-deposited produced by magnetron sputtering. The corrosion behavior was studied by potentiodynamic polarization and electrochemical impedance spectroscopy tests in blood bank buffered saline solution. It was found that the as-deposited alloy showed more than one order of magnitude reduction in corrosion current density compared to the cast alloy, owing to the elimination of micro-galvanic coupling between the Mg matrix and the precipitates. The microstructure and formation mechanism of corrosion products formed on both alloys were discussed based on immersion tests and direct measurements of X-ray photoelectron spectrometry (XPS) and cross-sectional transmission electron microscopy (TEM) analysis.