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Keyna O'Reilly

Professor Keyna O'Reilly
Associate Professor of Materials
Fellow of Queens College

Department of Materials
University of Oxford
16 Parks Road
Oxford OX1 3PH
UK

Tel: +44 1865 273743 (Room 110.10.02)
Tel: +44 1865 273777 (reception)
Fax: +44 1865 273764


Summary of Interests

Solidification processing of advanced materials from laboratory scale simulations through to pilot scale processing plant, with particular interests in grain refinement, melt conditioning and intermetallic phase selection. Also thermal analysis of phase transformations. Covering a wide range of materials, with particular interest in Al alloys and intermetallics.

Current Research Projects

Direct chill casting of Al alloys
Dr. K.A.Q. O'Reilly
The department has a one tonne direct chill (DC) caster which is being used to investigate the effects of alloy composition, processing parameters and grain refinement practice on the microstructures and properties of Al alloys.

Melt conditioning of Al alloys
Dr. K.A.Q. O'Reilly
This work involves developing novel thermal and chemical melt conditioning procedures for the control of microstructures during casting, and providing evaluation and measurement technologies for the same.

Liquid Metal Engineering (LiME) EPSRC Manufacturing Hub - Oxford spoke
S. Feng, A. Lui, Dr. E. Liotti, Professor P.S. Grant
The group is a partner in a new Engineering and Physical Sciences Research Council (EPSRC) funded £10 million Manufacturing Research Hub, which started in November 2015. The EPSRC Manufacturing Hub in Future Liquid Metal Engineering is led by Brunel University with major research activities at Oxford, Leeds, Manchester and Imperial College London, and involves a large number of industrial partners who will invest a further £45 million over the next 7 years. The UK metal casting industry adds £2.6bn/yr to the UK economy, employs 30,000 people, produces 1.14 million tons of metal castings per year and underpins the competitive position of every sector of UK manufacturing. However, the industry faces severe challenges, including increasing energy and materials costs, tightening environmental regulations and a short supply of skilled people. The group research will develop new approaches to X-ray imaging of solidification, including machine-learning techniques for automated image analysis. These techniques will be used to understand how impurities in liquid metals control microstructural evolution and how solidification conditions can be manipulated, for example by a pulsed magnetic field, to improve the tolerance of processes to impurities and so enable the increased re-circulation of metals in the manufacturing economy.

The role of secondary intermetallic phase selection on hot tearing of Al alloys.
T. Smith, Dr. K.A.Q. O'Reilly
Many aluminium alloys suffer from hot tearing (cracking) during casting due to high thermal stresses developed during solidification. The type, size and morphology of intermetallics formed during the final stages of solidification can affect hot tearing and correct manipulation of these intermetallics may lead to reduced hot tearing tendency. In this project, the morphology of the Al dendritic structure and the selection of secondary Al-Fe-Si phase intermetallics of an aluminium alloy are being seperately controlled, and their influence on the mechanical properties of the alloy in tension, at very low liquid fractions are being measured using a thermal mechanical analyser (TMA).

Microstructural control of Al alloys using intrinsic oxides
A. Verma, Dr. K.A.Q. O'Reilly, Professor P.S. Grant
The world produces 37 million tons of Al every year. All of this metal will have grain refiner additions made to it to promote the nucleation of a fine primary Al grain size. Oxide particles exist in nearly all liquid metals and alloys exposed to air or even under protective atmospheres. Oxide particles are often considered harmful inclusions since they reduce castability of alloy melts, deteriorate ductility and fatigue strength of castings and cause severe difficulties in down stream processing of continuous cast feedstock. As a result, considerable effort is expended to prevent oxide formation and to clean the melt by expensive melt filtering. However, recent research work at Brunel has demonstrated that by liquid metal engineering they can not only eliminate the harmful effects of the oxides but also make positive use of them for effective enhancement of nucleation for structural refinement of the Al grains, so reducing the need for grain refiner additions. Work in Oxford has demonstrated that grain refiner additions not only nucleate the Al grains, but also control intermetallic selection in Al alloys, hence modifying mechanical properties. This project is investigating the potency of oxide particles for heterogeneous nucleation of intermetallics. The nucleation sequence of various intermetallic phases due to unavoidable oxides and their control is being studied during solidification of Al-alloys. A phase extraction technique is being used to facilitate the detailed characterisation of intermetallic phases and their interaction with extrinsic and intrinsic alloy additions. Special reference is being made to inclusions and impurity elements in recycled materials.

Metal matrix composites produced by semi-solid processing
G. Wu, Dr. K.A.Q. O'Reilly, Dr. M.L. Galano
This project is using semisolid processing to obtain novel graded properties and selective local reinforcement of Al alloy components. The processing is based on the rapid induction heating into the semi-solid state of cylindrical slugs of materials containing various fine-scale complex microstructures. Stacking of slugs of various compositions will be used to obtain the gradation in properties or local reinforcement. Semi-solid material will subsequently be injected into an Ube 350 tonne New Rheocaster to produce components. Semi-solid techniques are known to produce small, equiaxed, non-dendritic grains resulting in an increase in the toughness of the material. Materials manufactured by this route will be suitable for use at a wide range of temperatures, dependent on the the Al alloy system. The applications the project will be focusing on are engine blocks and automotive and machine components. Different types of nano-sized reinforcements will be used in order to optimise the properties achieved in the final components. The fine scale complex microstructures of the composites obtained will need to be characterised at the different stages of the processing to gain an understanding of the processing/microstructure relationship and the microstructural evolution, to provide a platform to control the complex microstructures and to understand mechanical behaviour.

6 public active projects

Research Publications

Sha, G., O'Reilly, K.A.Q. and Cantor, B. (2006). 'Characterization of Fe-rich intermetallic phases in a 6xxx series Al alloy'. "Aluminium Alloys 2006, Pts 1 and 2". 519-521 1721-1726.

Srimanosaowapak, S. and O'Reilly, K. (2005). 'The relation between Al3Ti particle formation and impurity removal during in-situ precipitation treatment of Al-Ti-X alloys'. Shape Casting: The John Campbell Symposium, Minerals, Metals and Materials Society, Warrendale PA 41-50.

O'Reilly, K., Warren, P., Schumacher, P. and Cantor, B.: 'Special issue - Eleventh international conference on rapidly quenched and metastable materials - Preface.' Materials Science And Engineering A-Structural Materials Properties Microstructure And Processing 375-77 (2004) 1-1.

Srimanosaowapak, S. and O'Reilly, K.A.Q.: (2004). 'The improvement of melt quality after in-situ precipitation of Al3Ti particles in an Al-Ti alloy'. Light Metals And Metal Matrix Composites. Montreal, Canadian Inst Mining, Metallurgy And Petroleum: 283-297.

Sha G., O'Reilly K.A.Q., Cantor B., Titchmarsh J.M. and Hamerton R.G.: 'Quasi-peritectic solidification reactions in 6xxx series wrought Al alloys' Acta Materialia 51, 1883-1897 (2003).

Projects Available

Metal matrix composites produced by semi-solid processing
K. O'Reilly / M. Galano / F. Audebert

The aim of this project is to use semisolid processing to obtain novel graded properties and selective local reinforcement of Al alloy components. The processing is based on the rapid induction heating into the semi-solid state of cylindrical slugs of materials containing various fine-scale complex microstructures. Stacking of slugs of various compositions will be used to obtain the gradation in properties or local reinforcement. Semi-solid material will subsequently be injected into an Ube 350 tonne New Rheocaster to produce components. Semi-solid techniques are known to produce small, equiaxed, non-dendritic grains resulting in an increase in the toughness of the material.Materials manufactured by this route will be suitable for use at a wide range of temperatures, dependent on the the Al alloy system. The applications the project will be focusing on are engine blocks and automotive and machine components.Different types of nano-sized reinforcements will be used in order to optimise the properties achieved in the final components. The fine scale complex microstructures of the composites obtained will need to be characterised at the different stages of the processing to gain an understanding of the processing/microstructure relationship and the microstructural evolution, to provide a platform to control the complex microstructures and to understand mechanical behaviour.

Also see homepages: Marina Galano Keyna O'Reilly

Recycling of Al alloys
K A Q O'Reilly

Reducing energy use is a major component of the UK’s policy for meeting its CO2 emission targets. Vehicle lightweighting, by replacing steel components with light alloy castings and wrought components, has been identified as one of the technologies with the greatest potential to contribute to this goal. Aluminium alloys are hence being used by the automotive and aerospace sectors. However, these industries are currently using primary grade aluminium, as recycled materials do not give adequate mechanical properties.  
A recent life cycle assessment for the Al industry showed that the production of 1kg of primary Al, when all the electricity generation and transmission losses were included, required 45kWh of energy and emitted 12kg CO2, whereas 1 kg of recycled Al required only 2.8kWh (5%) energy and emitted 0.6kg (5%) of CO2. Hence the use of recycled materials would considerably reduce the carbon footprint.
This project will investigate the ability of melt conditioning to improve the mechanical performance of recycled materials. Melt conditioning is defined as treatment of liquid metals by either chemical or physical means for the purpose of enhancing heterogeneous nucleation through manipulation of the chemical and physical nature of both intrinsic (naturally occurring) and extrinsic (externally added) nucleating particles prior to solidification processing. A prime aim of melt conditioning is to produce solidified metallic materials with fine and uniform microstructure, uniform composition and minimised cast defects and hence good mechanical properties.

Also see homepages: Keyna O'Reilly

Improving melt cleanliness
K A Q O'Reilly

Most metals have, at some stage in their processing, been in the liquid state. Such metallic melts can be chemically dirty (containing impurities and dissolved gases) and physically dirty (containing unwanted hard particles, oxide films etc). It is now becoming accepted that the cleanliness of a melt can significantly influence the ease with which a melt can be handled and cast, and the properties of the final components into which it is made. This project will investigate the effect of melt cleanliness in Al alloys. Novel intrinsic and extrinsic methods will be developed, including chemical doping and thermal excursions of the melt, in order to improve melt cleanliness. Melt cleanliness will be measured in-house both directly in the melt and by investigating the effect on primary grain size and properties. The effectiveness of these novel methods will be compared to current industrial methods such as rotary flux degassing and filtration. The overall aim is to develop new methods for improving melt cleanliness which are both quicker and cheaper than existing technology, while being suitable for use on an industrial scale.

Grain refiner additions, impurity levels and melt cleanliness have all recently been shown to individually affect secondary intermetallic phase selection in Al alloys. In turn, the type, size and morphology of such intermetallics can significantly affect the ability to carry out downstream processing and the mechanical properties of final components. This project will investigate the effects of combining these and other factors (such as solidification conditions) in order to determine the dominant factors affecting intermetallic selection under more realistic, commercially relevant conditions.

Grain refiner additions, impurity levels and melt cleanliness have all recently been shown to individually affect secondary intermetallic phase selection in Al alloys. In turn, the type, size and morphology of such intermetallics can significantly affect the ability to carry out downstream processing and the mechanical properties of final components. This project will investigate the effects of combining these and other factors (such as solidification conditions) in order to determine the dominant factors affecting intermetallic selection under more realistic, commercially relevant conditions.

Also see homepages: Keyna O'Reilly

Microstructural control of Al alloys using intrinsic oxides
K O'Reilly

The world produces 37 million tons of Al every year. All of this metal will have grain refiner additions made to it to promote the nucleation of a fine primary Al grain size.
Oxide particles exist in nearly all liquid metals and alloys exposed to air or even under protective atmospheres. Oxide particles are often considered harmful inclusions since they reduce castability of alloy melts, deteriorate ductility and fatigue strength of castings and cause severe difficulties in down stream processing of continuous cast feedstock. As a result, considerable effort is expended to prevent oxide formation and to clean the melt by expensive melt filtering. However, recent research work at Brunel has demonstrated that by liquid metal engineering they can not only eliminate the harmful effects of the oxides but also make positive use of them for effective enhancement of nucleation for structural refinement of the Al grains, so reducing the need for grain refiner additions.
Work in Oxford has demonstrated that grain refiner additions not only nucleate the Al grains, but also control intermetallic selection in Al alloys, hence modifying mechanical properties. This project will investigate the potency of oxide particles for heterogeneous nucleation of intermetallics. The nucleation sequence of various intermetallic phases due to unavoidable oxides and their control will be studied during solidification of Al-alloys. A phase extraction technique will be used to facilitate the detailed characterisation of intermetallic phases and their interaction with extrinsic and intrinsic alloy additions. Special reference will be made to inclusions and impurity elements in recycled materials.

Also see homepages: Keyna O'Reilly

Also see a full listing of New projects available within the Department of Materials.