Abstract:

The electrochemical corrosion behaviour of the LY12CZ aluminium alloy, the L1(pure Al) and the intermetallic compounds of θ phase (CuAl 2),S phase (Al 2CuMg),and MnAl 6 was studied respectively in the Cl - ion containing neutral solution. These compounds were the main grain boundary precipitates of LY12CZ aluminium alloy. For each compound, the variation of the corrosion potential with time, and the anodic polarization curves were measured. Besides, the corrosion morphology and the corrosion products were studied by SEM and EDAX. The results showed that the pitting corrosion occurred there in all the phase, among others the corrosion resistance of S phase was the poorest and the L1 phase was the best. The pitting resulted mainly from the anodic dissolution of Al and Mg. The corrosion products were mainly insoluble aluminium hydroxides,soluble aluminium chlorides and soluble magnisium salts. The Cu and Mn were cathode of the microelectrochemical cells during the pitting corrosion.

Key words: electrochemical corrosion, intermetallic compounds, LY12CZ aluminium alloy