A novel fabrication method of surface-porous Mg-Al alloy and its corrosion property
By Wu, Peng-Peng; Zhu, Yi-Xing; Feng, Zhen-Liang; Song, Guang-Ling; Zheng, Da-Jiang
Published in Materials Today Communications
2021
Abstract
The specific stiffness, strength and damping capacity of a Mg alloy may be further enhanced if the Mg alloy has a specifically porous surface layer. However, it is not practical to use a faveolated brittle alloy precursor to generate such a porous microstructure. Hence, in this study, surface alloying was employed for the first time to fabricate the precursor of Mg-Al alloys with porous surfaces. The porous surface could be obtained via chemical etching of the precursor. The corrosion performance of the precursor alloy before and after the etching was measured and the corrosion mechanism was analyzed. It was found that in the alloyed surface layer of the precursor, the α-Mg was Al-supersaturated and potential difference of the α-Mg from the secondary phase was relatively small, which was helpful to form a uniform surface film to suppress micro galvanic corrosion. The porous surface had a high ratio of cathodic-to-anodic area and thus showed poor corrosion resistance compared with the surface of the precursor Mg-Al alloy.