Microstructural and high-temperature cyclic oxidation response of NiCoCrAlY coatings with and without SiC + ZrB2 reactive-element dispenser

•The SiC-ZrB2 can be used as a reactive-element (Si) compound dispenser.•Silicon behaves as a reactive-element reducing the oxidation.•Coatings with 1 % SiC-ZrB2 displayed thinner TGO layers and a lower oxidation rate.•Silicon seems to promote the stabilization of α-Al2O3 at earlier stages of oxidation. In this study, the microstructural and cyclic-oxidation evolution behavior of bond coats (BC) containing SiC + ZrB2 dispersed particles were evaluated. The SiC + ZrB2 dispersed particles at the oxidation temperature of 1130 °C, dissolved at early stages, stabilizing the beta phase, diminishing the aluminum outward diffusion. The silicon at the BC/TC interface, or very close to it, behaved as a reactive element promoting the rapid formation and stabilization of α-Al2O3 (TGO), and a second scale layer of mixed oxides and silicon-rich compounds, jointly limiting inward oxygen diffusion and resulting in thinner TGO layers, whose kinetic oxidation follows a sub-parabolic behavior, increasing oxidation life-span.