Effect of crystalline structure on the corrosion behavior of the Co-Cr-Mo alloy in 2.5 M H₂SO₄ + 0.2 M NaCl solution

Corrosion behaviors of Co-Cr-Mo alloys with fcc and hcp structures, respectively, were investigated by polarization tests and weight-loss method in 2.5 M H₂SO₄ + 0.2 M NaCl solution. Samples were heat treated and single-phase fcc samples, single-phase hcp samples and mixed-phase samples were obtained. Polarization tests and weight-loss method shows that the fcc Co-Cr-Mo alloy has better corrosion-resistant characteristic than the hcp Co-Cr-Mo alloy. It was also revealed that similar corrosion-resistant characteristic to the fcc single-phase was obtained even in a Co-Cr-Mo alloy having a mixed composition of the dominant fcc phase and a small amount of the hcp phase.