The influence of stabilization treatment on long-term corrosion resistance and microstructure in Er and Zr containing 5083 aluminum alloy

Abstract

The effect of stabilization annealing on the long-term corrosion resistance and microstructure in Er and Zr contained 5083 aluminum alloy was studied using the nitric acid mass loss test (NAMLT), exfoliation corrosion (EC) test, accelerated sensitization annealing (ASA) at 175 °C and transmission electronic microscopy (TEM) observation. The results showed that the alloy in cold rolling state sensitized severely after the ASA. The long-term IGC and EC resistances improved significantly through stabilization treatment at 220 °C. The longer stabilization time, the better long term corrosion resistance. The precipitation evolution of the alloy during the ASA in cold rolling state and stabilization state were analyzed by TEM. The results showed that the β precipitates were not found at cold rolling state, but formed continuously along grain boundary during ASA at 175 °C for 2 h. After 12 h stabilization treatment from the cold rolling sample, β precipitates were isolated at the triple junctions and Al6(Mn,Fe) phase boundaries. During the further ASA at 175 °C for 2 h, β phases formed sparsely and separately at grain boundaries. The addition of stabilization treatment led to the morphology change of β phases during ASA, resulting in the improvement of long-term IGC resistance. Its mechanism was discussed thermodynamically and kinetically.