High-energy X-rays from a synchrotron radiation source, SPring-8, are available to obtain the microstructural information at deep positions inside the materials, because of its large penetration depth. Using the high-energy X-rays with an energy level of about 73keV, the internal stress in the bond coating was measured through the top coating in the thermal barrier coatings (TBCs) which consisted of a zirconia top coat with thickness of 0.24mm and a NiCoCrAlY bond coat with thickness of 0.2mm. A furnace, which could heat up the specimen up to 1473K was developed for the purpose of the in-situ stress measurement of the TBC in the goniometer at Beam Line BL02B1 of SPring-8. The diffraction of Ni3Al-311 from the bond coat obtained through the top coat with about 0.24mm thickness was strong enough for stress determination. The internal stress in the bond coating was measured at the room temperature, 773K, 1073K and 1373K. The internal stress in the bond coat at a room temperature was tensile, and it was decreased with increase in temperature. At 1073K or higher, the internal stress in the bond coat was released due to softening of the bond coat. The change of internal stresses in the bond coat with temperatures was explained by thermal mismatch of expansion between top and bond coats.
