Modeling non-linear temperature dependence of thermal expansion coefficient in Ni-based superalloys

The compatibility in coefficients of thermal expansion (CTE) between components is crucial in designing materials that can withstand large temperature variations without cracking or failing. For commercial Ni-based superalloys, which are important for aerospace applications, experimental measurements have shown that CTEs can exhibit a non-linear temperature dependence near the solvus temperature of γ′(L1 2 ) precipitates. Existing models in the literature often fail to describe this non-linear dependence, as they typically assume linearity or apply only to specific model alloys, ignoring the nuances of composition and heat treatment. In this work, we present a multi-phase CTE model calibrated using experimental data, from which the effect of chemical composition on CTE of each phase is determined. Effect of heat treatment is considered by calculating the phase fraction at treatment temperature. The model-predicted CTE agrees well with experimental measurements for commercial Ni-based superalloys. Based on the model predictions, suggestions for developing new composition and heat treatments to tune the CTE of Ni-based superalloys are proposed.