Physics of dislocations and plasticity


A part of our research activities aim at a better understanding of dislocations and elementary mechanisms of plasticity, in bulk materials or in nanostructures, and of the resulting properties at the macroscopic scale. The characterization and modelling of the properties of defects such as dislocations, grain boundaries, is the main focus.

 

Fig.: TEM image of a Al/Al-Cu-Fe composite deformed at room temperature.

 

 

 

 

 

 

 

Investigated materials include model materials (semiconductors, oxides, metals) on the one hand, and systems with a more complex structure (MAX phases, multiphased materials and/or nanocristalline). Mechanical properties of these materials are determined by deformation test within various thermomechanical conditions (tension, compression, relaxation, creep, deformation with confining pressure). Corresponding microstructures are characterized by transmission electronic microscopy. In situ deformation techniques are also used for investigating the dynamical aspect of the interplay between microstructure and deformation mechanisms. Simulations with molecular dynamics and first principles calculations are also performed for studying the details of intteractions. The use of specific experimental devices allowing to reduce the fragility of materials and to reach high stresses is an original feature of our activity.

 

Research topics:

First stages of plasticity in nano- and micro-objects: simulations and experiments

“Fundamentals of the deformation mechanisms in the MAX phases”

Microstructure and plasticity of nanocomposite materials processed by severe plastic deformation

Fabrication, Structure and Mechanical Properties of Metal-Complex Intermetallic composite Materials

“Mapping the local mechanical properties of heterogeneous materials by nanoindentation”

“Brittle-to-ductile transition in semi-conductors and dislocation core structure”








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