Submitted by ajw1 on Tue, 2011-09-06 13:42
In an effort to share ideas between universities with regard to MURI activities, participants will gather research updates in this area.
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The following information is included here as a Research Update from the October 2014 MURI Annual Report abstract:
The primary objective of this program is to establish a unifying scientific framework for a thorough understanding of the influence of grain boundary complexions on the performance of advanced materials. We plan to exploit the fundamental understanding in materials of strategic interest for enhanced processing and improved properties as well as for design and synthesis of bulk nanocrystalline materials and entirely new classes of materials with unique combinations of properties.
In the third year of this five year program, we developed complexion diagrams for Ni-Bi and Al2O3-ZrO2 materials systems. Additionally, we created a framework for developing time-temperature-transformation diagrams for complexion transitions. Research for developing such diagrams for alumina systems was initiated. It was observed that by controlling the processing temperature and energy of interfaces, it would be possible to control the rate of which a grain boundary complexion transformation occurs. The research on nickel alloys was expanded. The nucleation, stability and energetics of grain boundary complexions were studied via experimental and computational methods. Ternary alloys such as Ni-Bi-S were studied. The research on nano-grain Ni-W alloys was expanded to gain thorough understanding of the thermal stability of the grain structures in these materials. Based on experimental discovery of new second phases, an alternative hypothesis for the stabilization of nanograins by Zener pinning was proposed. We expanded the research on transport property measurements to determine the kinetics and thermodynamics of solute stabilized nanograined alloys, and characterize the effect of complexions and solute on cation lattice and grain boundary diffusion in Al2O3. A new processing route has been successfully developed to create novel nanoscale layered composites of metallic copper and θ-alumina.