Determination of mechanical properties of bondcoat materials by high temperature instrumented indentation

The integrity of thermal barrier coating systems is strongly influenced by themechanical properties of the different layers constituting them, in particular the intermetallic bondcoats. At high temperature, interdiffusion and oxidation phenomena cause change in the composition of the bondcoats and as a result their mechanical behaviour is likely to change also. Thus the knowledge of the mechanical behaviour of bondcoats is necessary to describe the stress field present in thermal barrier systems. To determine the mechanical behaviour of alloys, such as beta-(Ni, Pt) Al in bulk form and as bondcoats, a high temperature instrumented indenter capable of functionning up to 1000. degrees C is used. The technique is original and enables to investigate a large number of compositions and conditions within a reasonable time. From the experiments data, the mechanical behaviour of these materials is identified, as a function of the metallurgical evolution with temperature of bondcoats alloys. The results are discussed in relation to the mechanical properties obtained by other techniques.