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Abstract
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The present study investigated the influence of grain refinement on the passive and electrochemical response of 2024 Al alloy in a borate buffer solution. Optical microscopy and transmission electron microscopy (TEM) micrograph depicted that with increasing the pass number of accumulative roll bonding process, the grain size of samples decreased and ultra-fine grained structure achieved. Also, the X-ray diffraction (XRD) analysis revealed that mean crystallite size decreased with increasing the number of accumulative roll bonding passes. To investigate the electrochemical behavior, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and MotteSchottky (MeS) analysis was carried out. Potentiodynamic polarization plots demonstrated the augmentation of the corrosion current density with the number of accumulative roll bonding passes. EIS plots depicted that polarization resistance decreased by increasing the passes number of accumulative roll bonding process. Moreover, MeS analysis revealed that the donor density of the passive layers increased in a higher number of accumulative roll bonding passes.
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