Lead P.I. - Dr. Jason R. Trelewicz

Tailored microstructures incorporating grain and interphase boundaries provide energetically favorable sites for combating displacement damage due to irradiation as well as cavity formation from gaseous impurities introduced by implantation or transmutation. Mechanisms for enhanced sink efficiency and gaseous impurity desorption in nanostructured materials have been discussed in the context of their large interfacial area per unit volume, which can be stabilized by deliberately doping grain boundaries with solute that offsets their interfacial free energy.  On this basis, the hypothesis of this research is that, at doped metallic interfaces, changes in the local energy landscape due to chemical contributions from solute and associated structural transitions will dictate the critical impurity concentration for gas bubble nucleation. From this research, a new mechanistic understanding of defect formation and evolution in doped metallic interfaces will be realized, thus providing a critical step forward in the science of stabilized hierarchical structural materials. Example results are shown in the figure above of model nanocrystalline Mo-Au alloys including (a-b) experimental STEM HAADF/EDS images and (c-f) results from lattice Monte Carlo simualtions. Complementary molecular dyanmics simualtion results summarizing (g-h) the effect of doping grain boundaries on interstitital content.