Journal of Japan Institute of Light Metals

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In the previous study, we suggested that Ti addition could improve the intergranular corrosion (IGC) susceptibility of Al-Mn-Si-Cu-Mg alloys. It was considered that the potential gap due to the Ti layered distribution prevented the progress of IGC. Based on this mechanism, it was expected that the improvement effect on IGC due to Ti addition would be effective for various aluminum alloys that dissolve the solute-depleted zone formed near grain boundaries. In this study, we investigated the influence of additional Ti on IGC susceptibility of Al-Cu, Al-Mn, Al-Si, Al-Mg-Si, and Al-Mg-Si-Cu alloys using anodic dissolution tests. These alloys exhibited severe IGC susceptibility. However, IGC was improved by Ti addition. Nevertheless, depending on the heat treatment conditions, Al-Cu alloys showed high susceptibility to intergranular corrosion even when Ti was added. It was suggested that the effect of Ti was not obtained when the potential difference between grain interiors and grain boundaries was too large. It was concluded that Ti is effective in inhibiting the intergranular corrosion of various aluminum alloys if the potential difference between grain interiors and grain boundaries is less than approximately 40 mV.

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