Our proposed research for Phase I is in response to US Army solicitation for developing novel tungsten-based composites which offer the best properties for munition applications, particularly as kinetic energy penetrators. To meet this goal, we propose to produce, high purity, unagglomerated, engineered, nanocrystalline tungsten and titanium particlates in situ in the ration of around 10:1 as a model material, by incorporating a low-cost method called Gas Phase Combustion Synthesis (GCS) and consolidate the fine particulates to full density by Hot Pressing to replace the environmentally sensitive Depleted Uranium. Our W/Ti synthesis route involves a sodium-flame process together with a NaCl coating technique that prevents agglomeration. The byproduct-coating of individual tungsten grains and reduce tungsten to tungsten contiguity. Hot Pressing of the W/Ti particles will be conducted at lower temperatures and higher pressures to curtail the growth of tungsten grains. The resulting material via nanoscale technology, will have a microstructure containing nanocrystalline tungsten grains uniformly dispersed in titanium matrix (binder phase). The resulting microstructure will be unique and is expected to provide increased strength and fracture toughness and therefore, shear localization at reduced strain levels. The GCS process is equally applicable for synthesis of a variety of metals and composites. The process is attractive because scale-up is straightforward. In addition to synthesis and consolidation of 90W-10Ti, we propose to demonstrate the occurrence of shear localization in nanocrystalline 90%W-10%Ti by compression testing at strain-rate ~5000 s(-1) in order to simulate ballistic test conditions and enhance the usefulness of this material in defense and commercial sectors.
