Metals and Materials International ( IF 3.3 ) Pub Date : 2021-07-29 , DOI: 10.1007/s12540-021-01010-w Milad Johari 1 , Seyed Hadi Tabaian 1 , Shahaboddin Saeedi 1
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Abstract
Influences of heat-treatment and anodizing procedures on microstructure evolution and corrosion performance of two as-cast magnesium alloys containing different amounts of Ca and rare earth elements and same amounts of Zn were investigated, with the ultimate goal of developing a new biodegradable metallic implant. The first alloy (hereafter, denoted as F1) had higher RE element content but less calcium than the second one (denoted as F2). The same procedures of solution heat-treatment and aging were applied to alloys. Microstructures, together with the distribution and composition of secondary phases of all samples, were investigated by optical microscopy, field emission scanning electron microscopy, and energy-dispersive spectroscopy. Moreover, corrosion properties were evaluated in the phosphate-buffered saline solution using potentiodynamic polarization and also immersion tests at 37 °C. The results showed that corrosion performance is affected by both chemical composition and heat-treatment procedures. As-cast F2 has the least corrosion rate achieved by the polarization test. However, immersion test results show that solution heat-treated F1 has the lowest corrosion rate among all other specimens, including pure commercial Mg. In the next step, the anodizing process was performed in 3 current densities on solution heat-treated F1 alloy, and a 60% reduction in the corrosion rate was observed.
Graphic Abstract
中文翻译：
Mg-Zn-RE-Ca 合金作为可能的生物医学植入物的显微结构表征和腐蚀性能研究
摘要
研究了热处理和阳极氧化程序对含有不同量 Ca 和稀土元素以及相同量 Zn 的两种铸态镁合金的微观结构演变和腐蚀性能的影响，最终目标是开发一种新的可生物降解的金属植入物。第一种合金（以下记为 F1）的稀土元素含量高于第二种合金（记为 F2），但钙含量较低。对合金采用相同的固溶热处理和时效程序。通过光学显微镜、场发射扫描电子显微镜和能量色散光谱研究了所有样品的微观结构以及第二相的分布和组成。而且，在磷酸盐缓冲盐水溶液中使用动电位极化和 37 °C 下的浸渍试验评估了腐蚀特性。结果表明，腐蚀性能受化学成分和热处理程序的影响。通过极化测试，铸态 F2 具有最低的腐蚀速率。然而，浸泡试验结果表明，固溶热处理的 F1 在所有其他样品中具有最低的腐蚀速率，包括纯商业镁。在下一步中，对固溶热处理的 F1 合金以 3 种电流密度进行阳极氧化处理，观察到腐蚀速率降低了 60%。通过极化测试，铸态 F2 具有最低的腐蚀速率。然而，浸渍试验结果表明，固溶热处理的 F1 在所有其他样品中具有最低的腐蚀速率，包括纯商业镁。在下一步中，对固溶热处理的 F1 合金以 3 种电流密度进行阳极氧化处理，观察到腐蚀速率降低了 60%。通过极化测试，铸态 F2 具有最低的腐蚀速率。然而，浸泡试验结果表明，固溶热处理的 F1 在所有其他样品中具有最低的腐蚀速率，包括纯商业镁。在下一步中，对固溶热处理的 F1 合金以 3 种电流密度进行阳极氧化处理，观察到腐蚀速率降低了 60%。
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