Adventures in Alloys Group

Dr Samuel Rogers (Research Associate)

In collaboration with Rolls-Royce plc

Hardfacing alloys have been used for many years in components where surface degradation is of concern, particularly when coupled with extreme environments; be it high wear, high temperature, corrosive or erosive environments, or a combination of these. Of particular interest is the use of hardfacings in valve seatings within the pressurised water reactor (PWR) environment. This is a high temperature and highly corrosive environment in which wear and galling (severe adhesive wear) are of critical concern. The galling of components may result in gross surface degradation and component seizure, and is characterised by the plastic deformation and adhesion of contacting asperities. This is of concern since valve degradation may result in safety risks or reactor downtime, both of which being extremely costly to the operator. Galling has been found to occur most readily in systems which have limited movement perpendicular to the sliding direction such as in valves. This aim of this project is to set up a new galling rig at Imperial College, and to develop and test new Fe-based hardfacing alloys for valve seatings in PWR’s.

Dr Zachary Kloenne (Research Associate)

In collaboration with The Max-Planck-Institut für Eisenforschung GmbH

Investigation into the effects of hydrogen on the deformation and failure mechanisms in titanium alloys through use of correlative microscopy.

Alice Robinson (Research Postgraduate)

In collaboration with Rolls-Royce plc

Member of Nuclear Energy Futures CDT

TRistructural ISOtropic coated particle fuels (TRISO CPF) have been developed as a possible fuel solution for high temperature nuclear reactors, which offer the possibility of nuclear cogeneration-powered industrial facilities and hydrogen production. This project aspires at demonstrating the possibility to simulate the behaviour of this new type of fuel in a reactor and especially the behaviour of the interfaces between its layers with bond-based Peridynamics. Peridynamics is a non-local modelling technique which is an integral formulation of the finite element solution of continuum mechanics. The advantages of an integral approach are clear when crack formation and propagation are investigated, as it overcomes the limits of the partial differential equations representing most finite element models available to simulate the behaviour of materials.

The project focused on determining residual stresses arising during the fabrication of TRISO particles, validating the Peridynamics model against an experimental campaign of three-point-bend tests, and finally it will address TRISO layers behaviour during typical thermal transient in a reactor.

Yan (Gary) Gao (Research Postgraduate)

In collaboration with Rolls-Royce plc

Interaction between macrozones and stress concentration due to notch features are studied in Ti64 material in order to explain the fatigue life debit observed in high cycle fatigue regime.

Cameron Crabb (Research Postgraduate)

In collaboration with Rolls-Royce plc

From ingot and powder route starting points, the next steps for these superalloys are to develop them for additive layer manufacturing, ring rolling and extruded parts.

Dominic C Kwok (Research Postgraduate)

In collaboration with Rolls-Royce plc

Member of EPSRC Centre for Doctoral Training in Nuclear Energy Futures

Development of Fe-based replacements for Co-based hard-facing alloys for use in the light water reactor primary loop. This is done in hopes of reducing the impact of Co-irradiation, as Co has a large nuclear cross section and long decay half-life once irradiated.

Oscar Langdon (Research Postgraduate)

Co-supervised by Dr Shelly Conroy

In collaboration with Rolls-Royce plc

Member of Advanced Characterisation of Materials CDT

Titanium alloys have long been mainstays in aeroegine components due to their outstanding mechanical properties under high temperature, high stress, and, sometimes, impact prone conditions. However, they are known to experience cold dwell fatigue; when an engine is idling on a runway, the fans, discs, and blades may be spinning and therefor fatiguing with a dwell stress profile. It appears that operation in this cold condition can reduce the fatigue life of particular components very significantly. Understanding better the mechanisms behind these fatigue failures as they relate to cold dwell is hugely important in enabling a more accurate engine lifeing system. With a stronger understanding of these mechanisms we can develop the next generation of aeroengine alloys, and push Jet Propulsion that bit faster.