Evaluation of TBC-coated {beta}-NiAl substrates without a bond coat

{beta}-NiAl substrates with various alloy additions and oxide dispersions were coated with Y{sub 2}O{sub 3}-stabilized ZrO{sub 2} using electron beam-physical vapor deposition. Cyclic oxidation experiments (1000-1200 C) were conducted to study effect of substrate dopants such as Y and Zr on coating lifetime without the intermediate metallic bond coat layer used in conventional thermal barrier coatings. Oxidation kinetics and Al{sub 2}O{sub 3} scale microstructures were compared to those for uncoated substrates. Degradation of substrate-alumina interface by void formation was the primary mechanism leading to coating spallation. Coating lifetime was correlated to alumina scale adhesion on unocated substrates