Long-term corrosion tests of Ti 3 SiC 2 and Ti 2 AlC in oxygen containing LBE at temperatures up to 700 °C

Abstract Two MAX-phase materials, Ti 3 SiC and Ti 2 AlC, were tested at 550 °C, 650 °C and 700 °C up to 10 000 h in LBE (lead-bismuth-eutectic) containing of 10 −6 and 10 −8 wt% oxygen. It was found that secondary phases have a strong influence on corrosion effects. Ti 3 SiC showed a surface disintegration at 550°C/10 −6 wt% oxygen after longer exposure, while a 4–7 μm thick TiO 2 layer with Pb-Bi inclusions was detected on Ti 2 AlC. However, Ti 3 SiC is protected by a double layered oxide with an outer part of TiO 2 and a mixed inner layer of SiO 2 and TiO 2 at the higher temperatures. Ti 2 AlC formed a TiO 2 surface layer containing Al 2 O 3 . Some defects could be observed on the Ti 3 SiC surface in LBE containing 10 −8 wt% oxygen at 550 °C and 650 °C. The secondary phases between the Ti 3 SiC grains showed strong oxidation at 700 °C. Due to the high Al solubility in LBE, Ti 2 AlC experienced strong dissolution attack after longer exposure times at 650 and 700 °C.