In this study, the classical strengthening equations for weak and strong particles are advanced to account for oblate-shaped γ ″ precipitates in Inconel 718. The model is verified on quantitative stereology of size and distribution for both shearable and non-shearable mechanisms. The evolution of precipitation strengthening of aged superalloy Inconel 718 is simulated. In addition to precipitation strengthening, contributions of solid solution strengthening and the grain size effect are considered. Simulation results indicate a sound prediction of the final yield strength based on the presented model.

The number of fossil fueled power plants in electricity generation is still rising, making improvements to their efficiency essential. The development of new materials to withstand the higher service temperatures and pressures of newer, more efficient power plants is greatly aided by physics-based models, which can simulate the microstructural processes leading to their eventual failure. In this work, such a model is developed from classical nucleation theory and diffusion driven growth from vacancy condensation. This model predicts the shape and distribution of cavities which nucleate almost exclusively at grain boundaries during high temperature creep. Cavity radii, number density and phase fraction are validated quantitively against specimens of nickel-based alloys (617 and 625) tested at 700 °C and stresses between 160 and 185 MPa. The model’s results agree well with the experimental results. However, they fail to represent the complex interlinking of cavities which occurs in tertiary creep.