The objectives of this project are to demonstrate the materials and processing technologies needed to produce tungsten nanocomposite anti-armor penetrators that display superior penetration performance relative to conventional, tungsten heavy alloy penetrators while, at the same time, eliminating matrix alloying elements that are known or suspected to be toxic. A high volume, low-cost approach to synthesizing and safely consolidating tungsten nanocomposite powders to maximum overall density will be demonstrated, and the efficacy of these materials as potential replacements for depleted uranium (DU) in anti-armor penetrators will be assessed.
A number of studies have shown that microstructural refinement of tungsten can reduce its strain hardening and strain-rate sensitivity and thereby induce a shear localization response to high rates of strain, e.g. the type observed in anti-armor penetrator applications. However, for these materials to be seriously considered for deployment, their fabrication into high-density penetrators must be validated using approaches that are scaleable to high-volume production. In this project, two competitive, low-cost powder synthesis approaches--freeze-dry powders and glycine-nitrate synthesis--will be evaluated with respect to crystallite size, phase dispersion, sinterability, and potential for nanophase retention in the final consolidated material. Each is currently a proven, high-volume process for synthesizing nanocomposite and nanocrystalline powders. A series of high-volume powder consolidation processes also will be evaluated for their potential in yielding very high density and high ductility nanocomposite compacts, including combinations of sintering, hot isostatic pressing, swaging, and sinter forging. Based on these results, a single synthesis process and consolidation approach will be selected for further optimization and testing utilizing tungsten production equipment where possible. Results from high strain rate compression testing and measures of material producibility will be used as feedback data in evaluating process improvement. To validate the optimized processing conditions, prototype ballistic testing will be conducted using ¼-scale penetrator rods. Ongoing Department of Defense (DoD) health and environmental studies on tungsten-based materials will be monitored throughout the project. Based on the findings, nanocomposite samples may be submitted for toxicology testing.
Successful demonstration of a tungsten nanocomposite penetrator material that can replace DU and provide equivalent limit velocities against armor targets will allow DoD to field equivalent performance anti-armor munitions using a nontoxic penetrator material. The deployment of tungsten nanocomposite munitions will facilitate the decommissioning of the DU production base over the next decade, realizing a conservative 40-60% life-cycle cost savings for DoD operation of the anti-armor munitions production base, as well as eliminating the political, economic, environmental, and health issues inherent with the use of DU materials. (Anticipated Project Completion - 2011)