Oxide formation on titanium alloys in primary water of nuclear pressurised water reactor

Three titanium alloys were exposed to primary water at 300 degrees C. Oxides of the three alloys consisted of a dense layer and surface crystallites. The dense oxide layer of Ti CP was made of TiO₂ rutile whereas it was made of TiO₂ anatase for both Ti 64 and Ti10-2-3. Surface crystallites of the three alloys were composed of TiO₂ anatase and FeTiO₃ ilmenite. Oxide dissolution and precipitation phenomenon were found to play a key role in the corrosion mechanisms. Oxygen vacancies were identified as the main point defect responsible for the growth of the dense oxide layer. (authors)