Optimising Superalloys for Jet Engine Applications
Dr. Katerina Christofidou, University of of Sheffield, United Kingdom
As jet engines are continuously evolving to provide improved efficiencies culminating in reduced environmental and acoustic emissions, novel high temperature superalloy compositions tailored to these new service conditions are required. However, alloy design is a complicated task necessitating an in depth understanding of component requirements, physical metallurgy, the effects of chemistry on a multitude of properties as well as the impact of manufacturing and processing on the underlying material microstructures. In this seminar, two examples at different stages of the alloy development process will be presented.
The first part of the talk will focus on the thorough characterisation studies performed on the CM247LC alloy manufactured through laser powder bed fusion. Of particular interest to this work was the microstructural evolution of the material through different stages of post-processing including hot isostatic pressing and heat treatment. Electron microscopy studies, X-ray diffraction as well as resonant ultrasound spectroscopy were utilised to study the development of the microstructures after each post-processing stage. Selected results from these studies will be presented and the implications of these data on alloy design will be discussed.
The second part of the seminar will chronicle the design of a novel polycrystalline Ni-based superalloy for applications in jet-engine turbine discs. The alloy design strategy will be discussed starting from the initial scientific idea, based upon model quinary alloys, through to data collection and analysis that were used to define the alloy chemistries. Finally, the alloy compositions and their properties will be reviewed in comparison to an existing state-of-the-art alloy currently in use.
Dr. Katerina Christofidou is a Lecturer in Metallurgy at the University of Sheffield, having previously held research and project management roles at the Henry Royce Institute for Advanced Materials, the University of Manchester and the University of Cambridge. She holds a PhD in Metallurgy from the University of Cambridge and an MEng degree in Aerospace Materials engineering from Imperial College London. Her research focuses on the physical metallurgy of Ni-based and Co-based superalloys and their manufacturing through powder methods, as well as understanding the underlying metallurgy and thermodynamics of transition metal high entropy alloys. Throughout her career she has worked at the interface between industry and academia, delivering meaningful metallurgical insights. Her work with Rolls-Royce has led to several patents, namely on new Ni-based alloys for turbine disc applications, heat treatment optimisations for additively manufactured superalloys as well as new superalloys for manufacture through laser powder bed fusion. Her contributions have been recognised by awards from the Cambridge Society for the Application of Research, Churchill College Cambridge and the journal “Materials”.
This work was supported by Rolls-Royce plc and the Rolls-Royce/EPSRC Strategic Partnership under EP/H022309/1, EP/H500375/1 and EP/M005607/1.