Corrosion Behavior of Al-2wt%Cu Alloy Processed By Accumulative Roll Bonding (ARB) Process

Abstract

Accumulative roll bonding (ARB) imposes severe plastic strain on materials without changing the specimen dimensions. ARB process is mostly appropriate for practical applications because it can be performed readily by the conventional rolling process. An Al-2wt%Cu alloy was subjected to ARB process up to a strain of 4.8. Stacking of materials and conventional roll-bonding are repeated in the process. In this study, corrosion behavior of an Al-2wt%Cu alloy fabricated by ARB process was studied in 3.5%wtNaCl solution using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The morphology of structures was analyzed by scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX). Also, the electrochemical experiments showed that corrosion resistance of samples decreases with increasing the number of ARB cycles due to the formation of oxide layer on defects and energetic regions such as grain boundaries with low/high angle and high density dislocations accumulated in sub-grains. According to the nyquist curves, by continuing the process, the diameters of semicircles decreased and the corrosion resistance and the polarization resistance subsequently decreased. After 6-cycle ARB, link up of small pits and micro crack were seen. Also, with increasing the number of the ARB cycles, the mean grain size of specimens decreased and it reached to 650 nm after 6 cycles of ARB process.