A series of electrochemical tests combined with the techniques of scanning electron microscopy (SEM), electron backscatter diffraction (EBSD) and X-ray photoelectron spectroscopy (XPS) were used to study the effect of nitrogen content on the composition, structure and protectiveness of passive films, which were formed on the surfaces of high-nitrogen austenitic stainless steels (HNSS) in 0.5 mol/L NaCl solution. The results showed that the HNSS with higher nitrogen content had a larger proportion of low-angle grain boundaries, and it also had a lower corrosion current density in 0.5 mol/L NaCl solution and thus a lower corrosion rate. The existence of a larger proportion of stable oxides (e.g., Cr₂O₃) in the passive films facilitates the passivation/repassivation process and contributes to the high corrosion resistance of HNSS.

X-ray diffraction (XRD), scanning electron microscope (SEM), immersion, electrochemical, and tensile tests were employed to analyze the phase constitution, microstructure, corrosion behaviors, and tensile properties of a Ti-6Al-4V alloy and a newly-developed low cost titanium alloy Ti-4Al-2V-1Mo-1Fe. The results showed that both the Ti-6Al-4V and Ti-4Al-2V-1Mo-1Fe alloys were composed of α and β phases. The volume fractions of β phase for these two alloys were 7.4% and 47.3%, respectively. The mass losses after 180-day immersion tests in 3.5 wt.% NaCl solution of these alloys were negligible. The corrosion resistance of the Ti-4Al-2V-1Mo-1Fe alloy was higher than that of the Ti-6Al-4V alloy. The tensile tests showed that the Ti-4Al-2V-1Mo-1Fe alloy presented a slightly higher strength but a lower ductility compared to the Ti-6Al-4V alloy.

The formation of copper sulphide films on copper in aqueous sulphide solutions has been investigated under both natural corrosion and electrochemical conditions. Film growth occurs at the Cu₂S/electrolyte interface and involves Cu⁺ transport through a generally porous film. Both corrosion and anodic film growth are suppressed by high chloride concentrations. Passivity, a pre-requisite for pitting, is achievable only at high sulphide concentrations and transport fluxes, conditions not expected under most geologic repository conditions since both sulphide groundwater concentrations and diffusive transport rates are expected to be low. This paper is part of a supplement on the 6th International Workshop on Long-Term Prediction of Corrosion Damage in Nuclear Waste Systems.

The effect of chloride on copper corrosion in anaerobic aqueous sulphide solutions has been investigated using corrosion potential measurements, electrochemical impedance spectroscopy, scanning electron microscopy, focused ion beam and inductively coupled plasma atomic emission spectroscopy. Long-term exposure experiments were performed in 10⁻³mol L⁻¹ Na₂S solutions containing chloride concentrations in a range from 0.1 to 5 mol L⁻¹. Chloride was found to (i) inhibit Cu₂S film growth by displacing adsorbed sulphide from the Cu surface; (ii) induce film porosity; (iii) facilitate transport of Cu⁺ to the solution (at very high chloride concentrations). This paper is part of a supplement on the 6th International Workshop on Long-Term Prediction of Corrosion Damage in Nuclear Waste Systems.