Dobkowska Anna, Sotniczuk Agata, Bazarnik Piotr, Mizera Jarosław, Garbacz Halina
Faculty of Materials Science and Engineering, Warsaw University of Technology, 02-507 Warsaw, Poland.
Materials (Basel). 2021 Jan 14;14(2):394. doi: 10.3390/ma14020394.
In this work, the influence of bending an AA5457 alloy sheet and the resulting microstructural changes on its corrosion behavior was investigated. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to perform detailed microstructural analyses of the alloy in its original form and after bending. After immersion in naturally-aged NaCl under open-circuit conditions (0.5 M, adjusted to 3 by HCl), post-corrosion observations were made, and electrochemical polarization measurements were performed to investigate the corrosion mechanisms occurring on both surfaces. The results showed that the corrosion of AA5457 is a complex process that mainly involves trenching around coarse Si-rich particles, crystallographically-grown large pits, and the formation of multiple tiny pits around Si-rich nanoparticles. The experimental data showed that bending AA5457 changed the shape and distribution of Si-rich coarse particles, cumulated a higher dislocation density in the material, especially around Si-rich nanoparticles, and all of these factors caused that corrosion behavior of the AA5754 in the bending area was lowered.
在本研究中，研究了AA5457合金板材弯曲及其产生的微观结构变化对其腐蚀行为的影响。使用扫描电子显微镜（SEM）和透射电子显微镜（TEM）对原始状态和弯曲后的合金进行详细的微观结构分析。在开路条件下（0.5 M，用HCl调节至pH 3）将其浸入自然时效的NaCl溶液中后，进行腐蚀后观察，并进行电化学极化测量，以研究两个表面上发生的腐蚀机制。结果表明，AA5457的腐蚀是一个复杂的过程，主要包括围绕富硅粗颗粒的沟槽腐蚀、晶体生长的大坑以及富硅纳米颗粒周围多个小坑的形成。实验数据表明，弯曲AA5457改变了富硅粗颗粒的形状和分布，使材料中，特别是富硅纳米颗粒周围积累了更高的位错密度，所有这些因素导致AA5754在弯曲区域的腐蚀行为降低。
