Effect of Temperature on the Corrosion Behavior of CoCrNi Medium-Entropy Alloy in NH4Cl Solution

Effect of temperature on the corrosion behavior of CoCrNi medium-entropy alloy (MEA) in 3% NH4Cl solution was investigated by means of electrochemical measurements, immersion test and statistics analysis. The results show that increasing temperature makes it more difficult to form stable passive film on the MEA surface, accelerates the rupture of the film and reduces the anti-corrosion resistance of the MEA. Particularly at higher temperature, the corrosion rate of the MEA increases, as well the size and number of pits increase. In addition, NH4+ is further hydrolyzed with increasing solution temperature, which promotes the initiation and propagation of metastable pitting, slows down the re-passivation process and enhances the possibility of transition from metastable pitting to stable pitting.