Yield stress is one of the most important materials’ properties designers consider during material selection and is critical for service life performance of materials used in extreme environments. The
determination of materials’ yield stress in their operating environments is sometimes difficult to measure using classic tests. For coatings, operating at elevated temperatures, instrumented micro-indentation has now been developed to enable the determination of yield stress up to 1000°C of the coating itself without any modification of its structure due to sample preparation.

Under the micro-indentation stress field, high shear stresses and plastic deformation creating an opportunity to probe elasto-viscoplastic response of materials at the local scale. Using time dependent constitutive models, experimental results are analyzed to provide complete description of the equations describing the material’s response. In particular, yield stress can be extracted and results, as shown below, are comparable to results obtained from classic tensile tests.