Workshop 6

"High Energy X-Rays, Part II: Effects of Extreme Environments of Radiation, Temperature and Stress on Material Structure at Nanoscale – Role of X-Ray Probing and Visualization Techniques in Nanoscale Design"

Date: Tuesday, May 22, 2007

Organizer(s):
Nick Simos (Energy Sciences and Technology Dept., BNL) simos@bnl.gov
Lynne Ecker (Energy Sciences and Technology Dept., BNL) lecker@bnl.gov

Location: Bldg. 555, Chemistry, Hamilton Room

Description:

The next generation of nuclear power systems will require enhanced performance of materials that can safely operate under extreme irradiation, high temperatures, highly corrosive environments and high stresses. Progress in material science has resulted in a series of composites, ceramics and super-alloys that have been shown to exhibit “super” properties such as ultra-low elastic modulus, ultra-high strength, super plasticity and ultra-low expansion. These "super" properties are attributed to dislocation-free plastic deformation mechanisms associated with elastic strain fields that range from the nanometer scale to several tens of micrometers. Recent experimental studies, however, have shown that for a number of these super-materials, exposure to extreme environments such as radiation leads to serious compromise of their unique physical and mechanical properties. Therefore, fundamental understanding of the governing processes at the nanoscale level of the material structure and of the link with its macroscopic properties under these extreme conditions, processes such as kinetics of microstructure, defect generation, defect mobility and trapping, is a key requirement towards the “tailoring” of the nano- or micro-structure of materials in ways that will make them more tolerant to harsh conditions.

Envisioned are nano-structured materials that could be designed through iterative processes implementing vital information deduced from unique experiments focusing on what effects these extreme environments have at the nanoscale level. This would require, however, accurate probing of materials at the nanoscale level and that poses a serious challenge. Advancements in visualization techniques such as transmission electron microscopy (TEM), scanning TEM, electron tomography as well as those associated with synchrotron X-ray sources and in particular the Dispersive X-ray Diffraction and Phase Mapping, can provide the necessary probing means and allow the characterization and manifestation of induced damage in the material structure.

This workshop will provide the forum for (a) assessing the state of material engineering at the nanoscale that is relevant to the objectives and needs of the next generation nuclear and other novel energy systems as well as space applications, (b) identifying super-alloys and new materials that hold promise in meeting these stringent requirements, (c) discussing experimental evidence on the effects of the extreme environments on material structure, (d) identifying future experimental and possibly simulation-based activities that could help bridge the gap of understanding the underlying processes, and finally exploring the link between nanoscale material engineering and visualization techniques including the use of synchrotron X-ray sources as a viable tool in characterizing material response and damage at the nano- and micro-scales.