Microstructural Analysis of TMF Failure Mechanism of GTD-111 Applied to Gas Turbine Blades

Ni-based superalloys display excellent mechanical properties under high temperature conditions. Thermal barrier coating(TBC) technique protects the substrate from high temperatures and is, therefore, widely applied to industrial gas turbines and aircraft engines to enable them to endure severe enviornments. Thermo-mechanical fatigue(TMF) testing is a widely used method to evaluate the material properties and behaviors under the start-up and shut-down conditions of a gas turbine. In this study, to evaluate the microstructural failure mechanisms of Ni-based superalloys such as corrosion and metal diffusion at the surface and between coating layers, microstructural analysis was performed after TMF tests on specimens of GTD-111 applied to the 1st blades of industrial gas turbines. Also, the effect of TBC on the failure mechanism of GTD-111 was evaluated based on microstructural analysis of TMF tested specimens.