抄録
The effects of thermal shock on gamma-TiAl (γ-TiAl) intermetallic compounds and disilicide coatings on γ-TiAl (NbSi2/Nb/γ-TiAl) were evaluated by burner-heating methods. The burner-heating test consisted of a 1-min heating period and a 20-s cooling period. The number of cycles was 10. In the fifth cycle, the maximum surface temperatures of the γ-TiAl and NbSi2/Nb/γ-TiAl samples were the same at 1570 K, and the minimum surface temperatures were 640 K and 660 K, respectively. The temperature differences obtained for the γ-TiAl and NbSi2/Nb/γ-TiAl samples were approximately 900 K. After the burner-heating test, the γ-TiAl sample had a rough surface and a spalled scale which was expected to be a mixture of TiO2 and Al2O3. Continuous inner oxidation layer and discontinuous outer layer were observed, and SEM and EDX cross-sections showed that these layers were approximately 4 μm and 10 μm in thickness, respectively. The NbSi2/Nb/γ-TiAl sample was observed to have a smooth surface without a spalled scale. An oxidation layer was not observed on the NbSi2 surface. The NbSi2/Nb/γ-TiAl sample was not damaged by the burner-heating test.
