Grain boundary transport and related processes in natural fine grained aggregates. Progress report, August 15, 1991--August 15, 1992

摘要

We are pleased to report that all of the original research objectives will be realized by the end of the project period. In summary, we have developed a new technique for measuring grain boundary diffusion rates in polycrystalline aggregates and have successfully employed this technique to determine oxygen grain boundary diffusion rates in natural fine-grained quartz aggregates (novaculites) over a wide range of temperatures. In addition, we have demonstrated the major role of fluid composition on the microstructure and oxygen bulk diffusivity in a novaculite sample. Most recently, we have successfully produced hot-pressed fine-grained monomineralic quartz and feldspar aggregates and have measured oxygen grain boundary diffusion rates in these aggregates for comparison to the natural novaculite samples.