Corrosion of Ni–Ti alloys in the molten (Li,K) 2CO 3 eutectic mixture

Abstract

The corrosion of pure Ni and of binary Ni–Ti alloys containing 5, 10, and 15 wt.% Ti respectively in molten (0.62Li,0.38K) 2CO 3 at 650°C under air has been studied. The corrosion of the single-phase Ni–5Ti alloy was slower than that of pure Ni, forming an external scale composed of NiO and TiO 2. The two-phase Ni–10Ti and Ni–15Ti alloys underwent much faster corrosion than pure Ni, producing an external scale containing NiO and TiO 2, and a thick internal oxidation zone of titanium mainly involving the intermetallic compound TiNi 3 in the original alloys. The rates of growth of the external scales for the Ni–Ti alloys were reduced with the increase of their titanium content, while the internal oxidation was significantly enhanced. The corrosion mechanism of the alloys is also discussed.