Study on the microstructure and corrosion behavior of CoCrNi MEA annealed at different temperatures in Na2CO3/NaHCO3 solution.

The effect of different annealing temperatures on the corrosion behavior of CoCrNi medium entropy alloy (MEA) was investigated in an alkaline soil simulation solution. The results show the corrosion resistance of the MEA gradually increases with increasing annealing temperature. The corrosion behavior of the MEA is correlated with grain size, oxide inclusions, and surface passive film. With an increasing grain size, the proportion of grain boundaries decreases, which improves its corrosion resistance. The micro‐galvanic corrosion cell exists between the oxide and its surrounding matrix, which promotes the occurrence of pitting corrosion. As the annealing temperature increases, the film formed on the MEA surface becomes more complete and dense, greatly increasing the corrosion resistance of the MEA. [ABSTRACT FROM AUTHOR]