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TYC Lunchtime Seminar: Microscale Plasticity in Zirconium Alloys: Zirconium Hydrides and Second Phase Particles

Luca Reali

Department of Physics

Monday 17th February 2020
Time: 12.00pm
Venue: Room G01, Royal School of Mines
Contact: Ms Hafiza Bibi
Tel: 020 7594 7252

Abstract: In this talk, I am going to present the application of a computational technique known as discrete dislocation plasticity (DDP) to the problem of the structural integrity of zirconium alloys. These alloys are used in the core of fission reactors to clad the uranium fuel pellets. In the simulations, crystallographic dislocations are generated as a result of an applied load. This load may either be an external stress or it may come from other microstructural features. The dislocations are then free to move and form dislocation patterns, which we can analyse. The aim is to understand two distinct phenomena. The first is the fracture of thin zirconium hydrides, which are undesired precipitates that are always present, in service, in reactors where water is used as a coolant. The second is the plastic relaxation induced by second phase particles that precipitate in this material as a consequence of the alloying elements.

 

A completely innovative way of deploying DDP is presented, together with the results of this new model. It will be shown how the dislocation structures that emerge from the simulations of deforming hydrides suggest a mechanism responsible for their fracture. Those emerging from simulating the second phase particles, which are treated as misfitting inclusions, will offer a possible explanation for the observed segregation of solute atoms around them.

 

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