ELECTROCHEMICAL-BEHAVIOR OF QUASI-CRYSTALLINE ALLOYS IN CORROSIVE SOLUTIONS

The corrosion behaviour of quasicrystalline and related alloys is reported. A study of their resistance to electrochemical corrosion was performed using both direct current and electrochemical impedance spectroscopy techniques. Because these materials contain large amounts of aluminium, which as a pure metal forms a passivation oxide layer only from pH = 4 to pH = 8, the electrochemical response of the alloys was explored in a broad range of pH values. As a result, it is shown that the quasicrystalline state of the alloys improves the corrosion resistance thanks to the appropriate choice of composition but not as a consequence of a specific structure. The electrochemical properties observed in alloys of the present work differ from those of aluminium metals. As in stainless steel, the addition of chromium greatly improves the corrosion resistance. The effect of cracks and ingot heterogeneities is analyzed by impedance spectroscopy measurements.