Corrosion behavior of AlNiCoCuZr high-entropy equiatomic alloy in NaCl solution

Abstract

The service characteristics of high-entropy alloys, in particular their corrosion properties, are the subject of active study by many scientific groups. Interest to high-entropy alloys is determined by their relative simplicity of production (most often by arc melting with low cooling rates), corrosion resistance and high values of mechanical properties (hardness, strength). A special place among high-entropy alloys is occupied by compositions based on aluminum and transition metals (nickel, iron, cobalt) due to their service characteristics comparable with some bulk-amorphous compositions. For wider industrial application of such alloys, information on the peculiarities of corrosion processes therein is required. Corrosion behavior of Al₂₀Ni₂₀Co₂₀Cu₂₀Zr₂₀ alloy in water solution of 5 wt % NaCl as a result of exposure for 1500 h at 25oC was investigated in present work. It was found that the alloy was subjected to minimal corrosion due to dissolution of nickel and cobalt, with a corrosion rate of 2.98±0.01 mg/m2h. By electrochemical measurements, the value of corrosion potential was found to be –0.19 V relative to the chlor-silver reference electrode, and polarization to the anodic region resulted in selective dissolution of nickel and cobalt.