Composition and microstructure dependent corrosion behaviour of Mg-Li alloys
Composition and microstructure dependent corrosion behaviour of Mg-Li alloys
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镁锂合金的成分和微观结构相关腐蚀行为
DOI：
10.1016/j.electacta.2017.11.091
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发表时间：
2018-01-10
影响因子：
6.6
通讯作者：
Birbilis, N.
中科院分区：
文献类型：
--
作者：
Li, C. Q.;Xu, D. K.;Birbilis, N.
研究并比较了制备的超轻镁锂（Mg-Li）合金的腐蚀和电化学行为。选择所研究的合金组合物以提供比较独特的微观结构和晶体结构的能力，所述微观结构和晶体结构由Li的特定合金化添加引起。Mg-4%Li是六方密堆积（HCP）合金，其中Li在Mg（α-Mg）的固溶体中; Mg-14%Li是完全固溶体BCC（β-Li）合金，而Mg-7.5%Li是双相（α-Mg刺β-Li）合金。在0.1 M NaCl中的测试表明，Mg-Li系统的腐蚀性能和电化学响应随组合物和晶体结构而演变。Mg-4% Li合金腐蚀表面为丝状腐蚀形貌，Mg-7.5% Li合金腐蚀表面为α-Mg的丝状腐蚀和b-Li的局部溶解的混合腐蚀形貌。在BCC结构的Mg-14%Li合金的情况下，观察到轻微的点蚀，伴随着通常低的腐蚀速率（对于典型的Mg合金特别低的腐蚀速率），并且还揭示了随着暴露时间的增加的耐腐蚀性。暴露测试的组合，包括氢收集和质量损失，除了动电位极化和阻抗谱阐明和量化的三种不同结构的镁锂合金的腐蚀性能。结果表明，尽管由Mg和Li的活性元素组成，但具有BCC结构的β-Li相的形成可以促进形成高度保护性的表面膜，这导致Mg-14%Li合金的可预测的且一致的低腐蚀速率。(C)2017爱思唯尔有限公司版权所有
The corrosion and electrochemical behaviour of carefully prepared ultra-lightweight magnesium-lithium (Mg-Li) alloys were investigated and compared. The alloy compositions studied were selected to provide the ability to compare unique microstructures and crystal structures, which arise from specific alloying additions of Li. Mg-4% Li is hexagonal closed-packed (HCP) alloy with Li in solid solution of Mg (alpha-Mg); Mg-14% Li is a fully solid solution BCC (beta-Li) alloy, whilst Mg-7.5% Li is a duplex (alpha-Mg thorn beta-Li) alloy. Testing in 0.1 M NaCl revealed that the corrosion performance and electrochemical response of the Mg-Li system evolved with the composition and crystallographic structure. For Mg-4% Li alloy, filiform-like corrosion morphology can be observed on the corroded surface, whilst a mixture of filiform-like corrosion to the alpha-Mg and localised dissolution of b-Li existed on the corroded surface of Mg-7.5% Li alloy. In the case of the BCC structured Mg-14% Li alloy, minor pitting was observed, concomitant with a generally low corrosion rate (particularly low corrosion rate for typical Mg alloys) and an increasing corrosion resistance with exposure time were also revealed. A combination of exposure testing inclusive of hydrogen collection and mass loss, in addition to potentiodynamic polarisation and impedance spectroscopy elucidated and quantified the corrosion performance of three differently structured Mg-Li alloys. It revealed that in spite of being composed of reactive elements of Mg and Li, the formation of beta-Li phases with BCC structure could facilitate the formation of a highly protective surface film which results in a predictable and consistently low corrosion rate of the Mg-14% Li alloy. (C) 2017 Elsevier Ltd. All rights reserved.