Corrosion of magnesium (Mg) alloys and metallurgical influence
Corrosion of magnesium (Mg) alloys and metallurgical influence
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DOI：
10.1533/9780857091413.2.117
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发表时间：
2011
期刊：
影响因子：
--
通讯作者：
A. Atrens;Ming Liu;N. Z. Abidin;G. Song
中科院分区：
文献类型：
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作者：
A. Atrens;Ming Liu;N. Z. Abidin;G. Song
综述了决定典型两相镁合金腐蚀形式和腐蚀速率的以下方面：（i）测量细节;（ii）杂质元素铁、镍、铜和钴的浓度;（iii）第二相的体积分数、尺寸、分布和电化学;（iv）热处理;（v）环境引起表面膜形成和破坏的倾向;和（vi）α-Mg基质的组成。我们对镁腐蚀机制的理解是基于使用氯化物溶液的研究，这适用于汽车维修等应用。这些氯化物溶液具有相当强的侵蚀性。氯离子会破坏镁合金表面的部分保护膜。腐蚀速率随着暴露时间的增加而增加，直到达到稳定状态，这可能需要几个星期。这种理解可以阐明腐蚀的其他应用越来越重要的镁合金作为可生物降解的医疗植入物。阐明医疗应用的溶液倾向于形成表面膜，并且腐蚀速率随着浸泡时间而降低。表面膜增加了微观结构中微原电池之间的电阻，因此第二相颗粒对腐蚀速率的加速作用较小。表面状况是对镁部件腐蚀的附加影响。这对于汽车应用比对于医疗应用更重要，因为成本效益对于汽车应用更重要。
An overview is provided of the following aspects which determine the form and rate of corrosion of typical two-phase magnesium (Mg) alloys: (i) measurement details; (ii) concentration of the impurity elements iron, nickel, copper and Co; (iii) volume fraction, size, distribution and electrochemistry of second phases; (iv) heat treatment; (v) propensity of the environment to cause surface film formation and breakdown; and (vi) the composition of the a-Mg matrix. Our understanding of the Mg corrosion mechanism is based on research using chloride solutions, which are appropriate for applications such as auto service. These chloride solutions are quite aggressive. The chloride ions tend to break down the partly protective film on the Mg alloy surface. The corrosion rate increases with exposure time until steady state is reached, which may take several weeks. This understanding can elucidate corrosion for the other application of growing importance to Mg alloys as biodegradable medical implants. Solutions that elucidate medical applications tend to form surface films and the corrosion rate decreases with immersion time. The surface films increase the resistance between micro-galvanic elements in the microstructure, so that there is less acceleration of the corrosion rate by second phase particles. Surface condition is an additional influence on the corrosion of Mg components. This is of significantly greater importance for auto applications than for medical applications because cost effectiveness is much more important for auto applications.