For high temperature and load bearing applications, such as in hot-sections of airplane engines or stationary gas turbines, Ni-base superalloys are the material of choice. Their mechanical properties hold up very well at elevated temperatures even near their melting point. The main factor influencing this behaviour are the L1₂ ordered γ' precipitates which are distributed in the fcc γ matrix. The precipitate-dislocation-interaction is critical for the strength of the alloys. Even though the precipitates are coherent with the matrix, a perfect dislocation in the fcc matrix phase cannot enter a precipitate without surmounting an additional energy barrier. This is due to the ordered nature of the precipitates, which is disturbed by the dislocation and a stacking fault called anti-phase boundary (APB) is created. The strengthening contribution of individual precipitates is dependent on their sizes and their inter-precipitate spacings, also called channel width, but also on their overall volume fraction. [1]
Models that accurately describe this microstructure-property relation are of high interest for accelerating alloy and process development [2,3].In existing models often the mean values of these microstructural features are used to predict the mechanical strength. In this work, the prediction is generalized by using distributions of channel widths and precipitate sizes. We develop an algorithm for extracting the relevant distributions with high accuracy. This method delivers consistent results for 2D micrographs as well as simulated 3D microstructures. This is a clear improvement compared to the conventional line sectioning method. For the prediction of the materials yield strength, first, we determine the distribution of local strengthening by convolution of the microstructural parameter distributions with the strengthening functions. Finally, the yield stress is calculated by non-linear combination of the individual strengthening contributions.

References
[1] R.C. Reed The Superalloys – Fundamentals and applications, 2006, Cambridge University Press.
[2] E.I. Galindo-Nava; L.D. Connor, C.M.F. Rae Acta Materialia, 2015, 98, 377-390.
[3] A.J. Goodfellow, E.I. Galindo-Nava, C.W.M. Schwalbe, H.J. Stone Materials & Design, 2019, 173, 107760.