Characterisation of oxide scale adherence after the high temperature oxidation of nickel-based superalloys

Abstract

The scratch test technique was used to characterise the adherence of multi-layered oxide scales formed during the high temperature isothermal oxidation (1100 C) of a single crystal Ni-based superalloy AM1 with varying sulfur concentrations (0.22 -3.2 ppmw). Results were discussed in relation to cyclic oxidation behaviour and microstructural evolution of oxidised samples. The most commonly used elastic energy-based models were applied to calculate the work of adhesion. The obtained values of the work of adhesion were then analysed with regard to the mode-dependence of the fracture behaviour and the possible sources of errors in the scratch test results interpretation. This analysis allowed us to understand the limits of validity of these models and of the experimental value of the work of adhesion.