High temperature cyclic oxidation behavior of ferritic stainless steel with addition of alloying elements Nb and Ti for use in SOFCs interconnect

•Presence of Nb formed Laves-phase in the oxide/metal interface.•Inward diffusion of oxygen was reduced by Nb and Ti addition.•Nb and Ti addition were effective to enhance the oxidation resistance.

In the present work, high-temperature cyclic oxidation of ferritic stainless steel (FSS) with minor addition of Nb and Ti elements has been carried out at 800 °C in air for 70 cycles. Thermal cycling consists of 1 h heating in furnace followed by 15 min cooling to room temperature outside the furnace. The weights of all the specimens were measured every 1 cycle. The specimens were examined by scanning electron microscopy (SEM) and Energy-dispersive X-ray spectroscopy (EDS). The purpose of making this alloy was for application in solid oxide fuel cells (SOFCs) interconnects. The addition of minor alloying elements, especially Nb, led to formation of Laves phases in oxide/metal interface and prevented the diffusion of cation to the oxide scale. It is also a barrier for the influence of the oxygen anion to the inward of the FSS. The presence of high amount of Nb and low amount of Ti were effective on improving of the oxidation. By increasing amount of Ti compare to Nb in this steel caused the increased oxidation rate.