Al-Zn-Mg alloys have been investigated for the effect of Sc additions on corrosion resistance.The addition of Sc to Al-Zn-Mg alloys can more effectively retard recrystallisation during heat treatment and improve mechanical properties.Sc-added alloys show significant discontinuity in grain boundary precipitation.In addition,the distribution spacing of η precipitates at the grain boundary is the largest in the alloy with Sc content of 0.29 wt.%.The exfoliation corrosion test and microstructural recrystallisation analysis show the inhibitory effect of Sc addition on recrystallisation and hence the improvement in corrosion resistance.In-situ immersion corrosion results indicated that the uncorroded texture in Al-Zn-Mg alloy with 0.29 wt.%Sc content first showed a rapid decrease and then a rapid increase.The addition of Sc to Al-Zn-Mg alloy plays an important role in improving the surface texture and increasing the corrosion resistance in the early stages of corrosion.
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