Current Research Projects of Professor Alexander M. Korsunsky

Professor Alexander Korsunsky

Self-consistent Modelling And Diffraction Study Of BCC And HCP Polycrystals

A coordinated experimental and modelling study of polycrystalline deformation and internal stress development in polycrystals of important structural materials will be carried out. Diffraction of beams of penetrating radiation (neutrons at ISIS and ILL, and synchrotron X-rays at the ESRF) on samples and components subjected to residual and live in-situ stresses will be used to collect detailed data on the internal stress evolution during straining. The data will be used to develop and validate elasto-plastic self-consistent (EPSC) models for these materials.

The systems targeted in the present study are ferritic steels (as representative of bcc structure) and titanium alloys (hcp structure). The approach will be used to characterise the evolution of intergranular stresses during monotonic and cyclic loading of polycrystalline samples, which will give new and improved insight into the influence exerted by the internal stresses on the performance and service life of structural materials.

Sponsor

EPSRC

Internal Stress Evaluation Using Multiple Peak Laboratory X-ray Diffraction Analysis

The main thrust of the project is to develop the application of multiple peak diffraction analysis to stress determination in polycrystals using modern laboratory X-ray equipment. While significant amount of effort over the last decade has been devoted to synchrotron X-ray and neutron work in this area, the distinct and important implications for laboratory X-ray analysis only begin to be systematically explored. In situ monotonic and cyclic loading devices will be used in order to develop novel methods allowing the determination of the sample's deformation history, and its residual strength.

Sponsor

Oxford, EPSRC

Strain Scanning For Engineering Applications Using Synchrotron X-ray Radiation

The advent of the third generation synchrotron source at the European Synchrotron Radiation Facility (ESRF) in Grenoble opened up new possibilities for efficient use of X-rays to map internal stresses in engineering components non-destructively. The photon flux furnished by the modern insertion devices exceed that available in the lab by the factor of 10⁹, making measurements through over a centimetre of Al to the strain accuracy of 10^-4 possible during seconds. Joint development projects are carried out in collaboration with Manchester Materials Science Centre (Prof. P. J. Withers) and University of Salford (Prof. P. J. Webster) . Several beamlines are involved at the ESRF (ID31 Powder Diffraction, ID11 Materials Science) and SRS (16.3 Materials) and development of hardware and software solutions for engineering purposes is carried out.

Sponsor

ESRF, EU TMR

Indentation Of Coated Systems

Property determination of thin coatings from indentation measurements requires the development of sophisticated contact mechanics models. In collaboration with Dr A Constantinescu, of Laboratoire de Mecanique des Solides, Ecole Polytechnique, Paris, the concept of indentation response function is being developed and applied to elastically and elasto-plastically deforming coatings. Further developments aim to incorporate multilayers and functionally graded materials.

Sponsor

Royal Society

Design of coatings and coated systems

Coatings such as carbides, nitrides, dry film lubricants and multilayers are used in industry to produce drastic improvements in the hardness, low friction properties and hence performance of contacting components. Due to the extremely small layer thicknesses used the modelling and characterisation methods must be developed specifically for this class of problems. Instrumentation such as nanoindenters and atomic force microscopes are used to study the surface response and condition. Interpretation of the results requires understanding of the contact process, careful instrument calibration, and extrapolation towards the lowest loads, so that the coating-only behaviour can be extracted.

Lifeng Ma is working on his doctoral project concerning characterisation of contact deformation of coated systems, including the conditions of fretting fatigue and wear.

Sponsor

EPSRC