The Physics and Mechanics of Creep Cavity Nucleation and Sintering in Energy Materials

Lead Research Organisation: Open University
Department Name: Faculty of Sci, Tech, Eng & Maths (STEM)

Abstract

The research project will study the physics and mechanics of creep cavity nucleation and the reverse process of healing by sintering in polycrystalline materials for energy applications using both modelling and experimental approaches. The experimental work will focus on a model single phase material (commercially pure Nickel), a simple particle strengthened material (Nickel with addition of Carbon), a commercial austenitic stainless steel (Type 316H), a superalloy (IN718) and a martensitic steel P91/92. An array of state-of-the-art experimental techniques will be applied to inform the development of new physics-based cavity nucleation and sintering models for precipitation hardening materials. Once implemented in mechanical analyses, and validated, such models will form the basis for development of improved life estimation procedures for high thermal efficiency power plant components.

Planned Impact

The life of modern (and legacy) power generating plant is limited by the high temperature performance of the construction materials. But our continuing lack of understanding of the underlying processes controlling nucleation of creep cavities (i.e. damage) means that empirical models fitted to macroscopic data are currently employed by industry to assess creep failure and define safe operating life. The reverse process of cavity healing by sintering has received even less attention than nucleation, but is equally important in developing mechanistic understanding. The fundamental insights, knowledge and models arising from the proposed research programme will allow more physically based design and assessment procedures to be developed for high temperature power generating plant. This will help to underwrite life extensions of legacy power generating plant that are limited by the high temperature performance of the construction materials, as well as supporting future designs of power generating plant that must exceed a 60 year life specification. Moreover a deeper understanding of cavities sintering opens up new opportunities for designing components and thermomechanical histories that promote self-healing in-service and extending a component's life. The research project will have far reaching national and international academic impact because of the fundamental nature of the proposed modelling and experimental studies, widespread industrial impact owing to the potential for improving design methods and lifetime assessment procedures, societal benefits through improved assurance of fail-safe operation of power plant, substantial economic benefits arising from life extension of legacy power plant (and longer design life for new power plant), as well as the training of 3 post-doctoral researchers, 4 PhD students and the strengthening of leading UK research groups working in the high temperature materials field.

Publications

10 25 50
 
Description Beihang University 
Organisation Beihang University
Country China 
Sector Academic/University 
PI Contribution Preparation of crept copper and stainless steel samples containing nucleated cavities that have been characterised by Small Angle Neutron Scattering and SEM.
Collaborator Contribution Beihang's original offer to carry out HIPPING of samples containing creep cavities has been negatively impacted by Covid-19. The revised plan is for the UK partners to send samples for sintering in early 2021. Beihang has offered to host a joint meeting in China in 2022 towards the end of the project
Impact None yet owing to Covid-19 delays to experimental work.
Start Year 2018
 
Description Copper bi-crystal preparation 
Organisation Academy of Sciences of the Czech Republic
Country Czech Republic 
Sector Academic/University 
PI Contribution Provision of pure copper bar and technical exchanges.
Collaborator Contribution Preparation of copper bi-crystals for the project research studies at the University of Bristol and Oxford University.
Impact On-going
Start Year 2019
 
Description EDF Energy 
Organisation EDF Energy
Department EDF Energy Nuclear Generation
Country United Kingdom 
Sector Private 
PI Contribution The Open University, Bristol University and Oxford University are hosting project related PhD studentships co-funded by EDF Energy.
Collaborator Contribution 1. EDF Energy is co-funding PhD studentships associated with the project at the Open University, Bristol University and Oxford University. 2. EDF Energy is providing test materials as in-kind contributions. 3. EDF Energy is actively involved in studentships' supervision. 4. EDF Energy provides technical background information and specialist advice on the project aims, execution and outputs
Impact The PhD thesis of Markian Petkov (Oxford University)
Start Year 2018
 
Description EPRI Collaboration 
Organisation Electric Power Research Institute (EPRI)
Country United States 
Sector Charity/Non Profit 
PI Contribution 1. Bristol is co-funding a PhD studentship with EPRI. 2. Bristol has recruited a PhD candidate who started in December 2020 and will be co-supervised by the University of Oxford.
Collaborator Contribution 1. EPRI has co-funded a PhD student associated with the project based at Bristol University in collaboration with the University of Oxford 2. Jonathan Parker from EPRI has attended 3 project progress meetings and contributed his knowledge and expertise.
Impact PhD studentship contract between the University of Bristol and EPRI
Start Year 2018