Superior corrosion resistance of high-temperature Ir–Ni–Ta–(B) amorphous alloy in sulfuric acid solution

In this work, the corrosion behaviors and underlying mechanisms of high-temperature Ir-based amorphous alloys in an acidic solution were investigated systematically. The Ir-Ni-Ta-B amorphous alloy exhibits a crevice corrosion behavior with a superior corrosion resistance characterized by a low passive current density and a wide passive potential range. It is found that the high-exchange current density of H+ and H2 couple on the metalloid constituent can accelerate the active precipitation of passivation elements, leading to rapid formation of passive film. In sulfuric acid solutions, the formed passive film containing Ir, Ta5+ and Ni3+ oxides significantly increase the corrosion resistance.