Corrosion Behavior of Super High-Strength Cu-15Ni-8Sn-Zn-0.8Al-0.2Si Alloy after Heat Treatment with Different Processes

The designed super high-strength Cu-15Ni-8Sn-Zn-0.8Al-0.2Si alloy was treated with two kinds of heat treatments, peak aging and over aging. The corrosion behavior of the alloy heat treated with different processes was investigated by immersion corrosion test, polarization curve testing and micro morphology observation. The results show that the corrosion resistance of the peak aged alloy was better than that of the over aged alloy, and the peak aged alloy had more continuous and denser corrosion product layer compared to the over aged alloy. After the over aging treatment, granular and lamellar discontinuous precipitates occurred in the grain boundaries, resulting in the enrichment of nickel and tin elements, and forming miniature galvanic cells with the matrix to accelerate the corrosion of the alloy.