LIBRARIES Enhancing Stability of Powder-Route Nanocrystalline Tungsten-Titanium via Alloy Thermodynamics

Improvement in material properties as a result of grain size refinement to the nanoscale is often limited by an inherent tendency of these nanostructured materials to coarsen especially at the high temperatures required for processing. The structural instability stems from a large volume fraction of grain boundaries that carry an intrinsic energy penalty, but can be overcome by a consideration of the thermodynamics-based mechanism of interface energy relief via alloying. Suitable alloying conditions can provide a solute segregated grain boundary configuration that enables a nanostructured alloy to become the system's most energetically preferable state. A thermodynamics-based Monte Carlo method that captures the physics of regular solution mixing and grain boundary segregation in nanostructured alloys is developed and used to study the energetics and equilibrium structures of binary alloys. Our simulation is used to identify th