Influence of the lithium content on the negative difference effect of Mg-Li alloys
Influence of the lithium content on the negative difference effect of Mg-Li alloys
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锂含量对镁锂合金负差效应的影响
DOI：
10.1016/j.jmst.2020.03.046
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发表时间：
2020-11-15
影响因子：
10.9
通讯作者：
Han, E. H.
中科院分区：
文献类型：
--
作者：
Li, C. Q.;Xu, D. K.;Han, E. H.
所谓的“负差效应”（NDE）通常被定义为阳极极化下镁（Mg）表面析氢速率的增加。本文通过一系列的电化学测试和显微组织观察，证明了增加锂含量可以延缓镁锂合金的NDE。采用Mg- xli （x = 4、7.5和14 wt%）合金电极进行的恒电位、恒流和动电位极化实验表明，在阳极溶解前，Mg- 4li合金保持了与传统镁合金相同的增强NDE。在低阳极电流密度下，β - li相的出现削弱了双相Mg-7.5Li合金的NDE，但在高阳极电流密度（大于2 mA/cm(2)）时，NDE仍有明显增强。表面观察（包括平面形貌和横截面形貌）证实了由阳极溶解产生的裂纹表面膜导致了NDE对Mg-4Li和Mg-7.5Li合金的催化活性。此外，预先施加阳极极化后，Mg-14Li合金的NDE被明显抑制，这是由于表面膜的持久性和完整性，可以承受较高的外加阳极电位和电流。(C) 2020由爱思唯尔有限公司代表《材料科学与技术杂志》编辑部出版。
The so-called 'negative difference effect' (NDE) was often defined by the increasing rate of hydrogen evolution from magnesium (Mg) surface under anodic polarization. In this work, a series of electrochemical tests and microstructure observations were performed to provide an evidence that the NDE of Mg-Li alloys can be retarded by increasing lithium content. Potentiostatic, galvanostatic and potentiodynamic polarization experiments using Mg-xLi (x = 4, 7.5 and 14 wt%) alloys electrodes indicated that Mg-4Li alloy maintained the enhancing NDE prior to anodic dissolution as that of conventional Mg alloys. However, the emergence of beta-Li phase weakened the NDE of duplex Mg-7.5Li alloy at a low anodic current density, but it was still enhanced apparently after a high applied anodic value (more than 2 mA/cm(2)). The surface observations, including the plane and cross-sectional morphologies, confirmed that the cracked surface film derived from the anodic dissolution resulted in the catalytic activity of NDE for Mg-4Li and Mg-7.5Li alloys. Furthermore, the NDE of Mg-14Li alloy was suppressed obviously after a prior applied anodic polarization, which was attributed to the persistent and integrated surface film which endured a higher level of applied anodic potential and current. (C) 2020 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.