Characterization of the alumina scale formed on coated and uncoated doped superalloys

► Study of alumina scale formed after exposure (100 h/1100 °C) on bare and coated CMSX4 and modified CMSX4 with La + Y. ► On bare superalloys only Hf was found at the alumina grain boundaries near the metal-scale interface (no Ti). ► Only single Al2O3 layer formed on all coated superalloys with Hf and Y presents within the grain boundary scale. ► No La segregation on alumina grain boundaries on either bare or coated superalloy. ► Ti-rich oxide precipitates in Al2O3 scale in coated superalloys suggesting interdiffusion through the coating.