Synergistic effects of Pt and Y addition in (Ni, Pt)CrAlY bond coat on oxide spallation resistance and growth of interdiffusion zone between bond coat and Ni-based single crystal superalloy

This study shows the beneficial effect of Pt addition to the (β+γ)-NiCrAlY coating. Adding Y in NiCrAl increases oxide growth kinetics but improves spallation resistance. Pt with Y does not change the oxidation rate compared to only adding Y but significantly reduces spallation when cooled to room temperature. Continuous layers of Al 2 O 3 and Cr 2 O 3 , along with other oxides such as YAlO 3 , NiCr 2 O 4 , and NiAl 2 O 4, are observed. Moreover, Pt addition reduces the thickness of the interdiffusion zone where Al goes through an uphill diffusion profile, minimizing Al loss and significantly decreasing the growth of deleterious TCP phases. • Pt addition to (β+γ)-NiCrAl improves spallation resistance without affecting oxide growth kinetics. • Y addition increases oxide growth kinetics but improves spallation resistance. • Combined Pt and Y additions markedly enhance oxide layer spallation resistance. • TEM reveals α-Al 2 O 3 and Cr 2 O 3 oxide layers, spinels and Y-Al-rich oxide pegs at the bond-coat/Al 2 O 3 interface.