A single misplaced grain in a nickel superalloy turbine blade can render the entire casting unusable, and Rolls-Royce wants to know exactly why that happens. The hottest parts of a jet engine are made from single-crystal superalloys, where billions of atoms align in perfect order. But during casting, a secondary grain sometimes forms—a "bicrystal"—creating atomic-scale defects that drastically shorten component life. Current safety criteria reject many of these castings, but the mechanisms behind bicrystal formation remain poorly understood. This project aims to build the world’s first high-fidelity simulation of how these defects nucleate and grow, from solid through semi-solid to liquid states. If successful, the research could reduce waste in manufacturing expensive turbine components and enable engine designs that run at higher temperatures. That directly affects fuel efficiency for electric and hybrid-electric aviation—a central challenge for the industry. The work combines physical metallurgy, advanced numerical modelling, and real manufacturing data from Rolls-Royce to ensure the simulations target practical improvements. This is fundamental science with a clear industrial destination: safer, more efficient engines and fewer scrapped castings.
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The rapidly evolving landscape for aviation propulsion - shaped by FlightPath 2050 objectives, commercial pressures, likely legislation, and crucially, a changing public demand - means that Rolls-Royce's grand challenge is now the electrification of flight. Miniaturised turbine-driven electrical generating systems will be required to power steady-state electric flight, enabling aircraft to vastly exceed the fuel economies of today. This necessitates both scaling and enhancing existing engine designs and the components within them or radically new designs. The principal determinant of aero engine efficiency is the temperature of operation of the turbine, in which much of the energy in the hot gas from the combustor is used to drive the front end of the engine, both the compressor to sustain combustion and the fan to create and amplify thrust. The components of the hottest part of the turbine are manufactured from nickel superalloys using casting technology developed and refined over decades to produce single crystals. Single crystal (SX) castings are each comprised of more than 10^24 (1 with 24 following zeros) atoms arranged in common alignment to a unit cell - the atomic scale 'building block'. This imbues them with astonishing strengths but also mechanical properties under load that vary with direction relative to the unit cell. Furnace technologies to make SX superalloy castings are highly advanced, being designed to avoid breakdown of the solidification front that moves slowly through the casting allowing atoms to be added to the prior solid. However, sometimes a secondary misoriented grain is formed, within which the atoms are aligned to a unit cell of different orientation; in the boundary there are missing atoms and bonds, as well as different structures - the "bicrystal". A large proportion of castings that contain bicrystals cannot be used as their function is considered to result in excessive decrease in component life. Criteria for their rejection favour safety in service. The mechanisms of bicrystal formation are not at all well understood. Physical and process metallurgy remains a cornerstone of engineering and manufacturing. Only by having a sufficiently detailed mechanistic understanding and models to predict how materials behave can their performance in service under ever more demanding conditions be predicted with confidence. Their safe use demands that limits of capability are understood and in turn mechanistic understanding stimulates the development of improved materials and processes for future applications. New or improved alloys and technologies often provide economic impact through increased commercial competitiveness. The strategic goal of this Prosperity Partnership for Advanced Research into Crystallographic Anisotropy & Nucleation Effects in single crystals (ARCANE) is to understand the nucleation of defects in the anisotropic world of single crystal casting. Our aim is to achieve the world's first high fidelity simulation of the nucleation and growth of bicrystals in the solid, semi solid and liquid regimes of the casting process. We aim to understand the associated materials properties of the anisotropic superalloy single crystals, as well as the properties associated with bicrystals formed during casting. This level of simulation will require breakthroughs at all levels, including physical models, numerical solvers and novel algorithms. We will use state of the art casting experimentation and materials evaluation to verify the models that we develop during the research. Furthermore, we will use the vast store of Rolls-Royce manufacturing and in engine data to ensure that our modelling and physical experimentation is targeted specifically for improvements
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