TiAlCrY has been used as a bonding layer for the thermal barrier coating (TBC) system on TiAl alloys, due to its excellent high temperature oxidation resistance. However, it was found that vertical cracks formed in the TiAlCrY layer during the thermal cycling tests, which would fasten the failure of TBC system. In this work, a TiAlCrNb buffer layer was introduced between TiAlCrY layer and the substrate to alleviate the nucleation and propagation of cracks in the TiAlCrY layer from the perspective of alleviating the stress concentration, aiming to improve the thermal cycling lifetime of the YSZ/TiAlCrY system. The results show that the thermal cycling lifetime of the newly designed YSZ/TiAlCrY/TiAlCrNb system was over 245 cycles by means of water-quenching, which was almost twice of the system without the buffer layer and 3-4 times of the traditional YSZ/MCrAlY system on superalloys. The influence of the TiAlCrNb buffer layer was analyzed based on the combined analysis of microstructure, residual stresses and mechanical properties. This work implies that a proper buffer layer could effectively improve the thermal cycling lifetime of TBCs on TiAl alloys.
NSTL
Elsevier