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Accueil > Séminaires > Séminaires passés > Séminaires de 2008 > Self-organization in metals driven by ion irradiation or severe plastic deformation

Robert S. Averback

Self-organization in metals driven by ion irradiation or severe plastic deformation

Le 10 octobre 2008, à 15h

A material subjected to sustained driving forces constitutes a dissipative system since it receives a continuous energy flux from its environment, energy which is partly converted into heat, but also partly in shifting atomic locations and creating defects. In such dissipative systems, a delicate balance is established between the dynamics imposed by the external forcing, and the internal dynamics of the system, and this balance controls the structural evolution of the material. By varying relevant forcing parameters, for example ion flux during irradiation, or shearing rate during severe plastic deformation (SPD), one can alter this balance and thereby induce dynamical transitions from one steady state to another with remarkable control. At the University of Illinois we have been exploring self organization in metals during either irradiation or SPD and find that under certain conditions some metals form patterns with a fixed nanometer length scale. A few examples of self organization are illustrated in this presentation : surface patterning during irradiation-induced dewetting and compositional patterning during ion irradiation or SPD. Noteworthy is that the ultrafine length scale of the patterns can be stabilized to very high temperatures.