Microstructure evolution and cyclic oxidation performance of Cr2AlC as active diffusion barrier for NiCrAlY coating on TiAl alloy

Abstract

Cr2AlC diffusion barrier was prepared between NiCrAlY coating and TiAl alloy. Long-term cyclic oxidation was conducted at 900 °C in air for 1000 cycles(h). Cr2AlC and transformed Cr7C3, α-Cr and TiC had significant blocking effects on Ti diffusion. So, the Al-rich phase in the NiCrAlY coatings was NiAl rather than Ni2TiAl, which inhibited the generation of TiO2 and avoided the presence of α-Cr in the Al2O3 scales. As a result, the stability and spalling resistance of the Al2O3 scales were enhanced.