Electrochemical Microalloying of Tungsten for Plasma Facing Component Applications

Tungsten¿s inherent chemical inertness and high melting temperature make it an ideal heat sink and armor material for fusion applications. However, tungsten¿s intrinsic low temperature brittleness makes it difficult to fabricate using conventional processing techniques. Recently, advanced electrochemical forming techniques based on microalloying and grain refinement have been developed that enable the near-net-shape fabrication of tungsten components. Based on these results, this project will develop near-net-shape, electrochemical processing techniques for the fabrication of fine-grain tungsten alloys for use in fusion devices. By proper selection of the alloying elements and processing parameters, it may be possible to tailor a tungsten alloy that resists grain growth, has improved strength and ductility, possesses good thermal conductivity, and is resistant to transmutation. During Phase I, the ability of electrochemical processing parameters to control the microstructure of deposits was evaluated, along with the ability to produce tungsten alloys. Preliminary microstructural analysis and testing verified that structural and properties improvements are possible using these techniques. During Phase II, the process will be optimized with respect to the electrochemical processing parameters and the amount of alloying additions. The optimized process will then be used to produce an advanced tungsten alloy heat sink, which will be high-heat-flux tested and compared to pure tungsten heat sinks. Commercial Applications and other Benefits as described by the awardee: The near-net-shape forming of tungsten alloys with improved ductility and mechanical properties has tremendous commercial potential. Aside from nuclear fusion applications, electrochemical microalloyed tungsten should be applicable to non-eroding nozzles in rocket engines, crucibles for crystal growth, heat pipes, welding electrodes, x-ray targets, warhead penetrators, radiation/temperature shielding applications, and other high temperature furnace components.