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Multiscale modelling of precipitation strengthening in superalloys


Supervisor: Peter Brommer

The extraordinary strength of superalloys is derived from precipitates – nanoscale inclusions embedded in the material. These strengthen the material by hindering the motion of dislocations, which are responsible for material deformation. Dependent on the material, the precipitates can come in a distribution of sizes and shapes. This project explores the effect of these variations on the properties of the material. A better understanding of precipitates will lead to rational criteria for the design of new high strength alloys that would increase the efficiency of turbine products and new engine designs.

In this project, the effects of variations in precipitate properties in precipitation-hardened alloys will be studied using a hierarchy of simulation methods, from atomistic Molecular Dynamics to Discrete Dislocation Dynamics or Crystal Plasticity, where smaller scales will inform larger scale simulations. Potentially, computational homogenisation approaches will be employed. At the end of the project, we understand how variations in precipitate morphology impact the properties of the material, thus quantifying the sensitivity of macroscopic quantities on nanoscale properties (e.g., precipitation shape).

The project is linked to an ongoing HetSys PhD project which is exploring the precipitate formation in superalloys. Initial results from that project could inform precipitate shape and size distribution as an input to this project. In combination, both projects would provide predictive models of precipitation hardening in superalloys.

This project will be undertaken in collaboration with our international partners at FAU Erlangen-Nürnberg (Prof. Erik Bitzek) and Universität Stuttgart (Prof. Siegfried Schmauder).

The background image (by H. Lyu, E. Bitzek, FAU Erlangen-Nürnberg) shows a pair of dislocations (lines of red atoms) approaching irregularly shaped precipitates (dark grey). The inset image on the left shows pairs of dislocations crossing precipitates in different sizes. On the right, a pair of dislocations is shown crossing through precipitates. Inset images adapted from Kirchmayer, Lyu, et al., Adv. Eng. Mater 22: 2000149.