Rhines Hall, Room 125
549 Gale Lemerand Drive
Gainesville, FL 32611
Join the Department of Materials Science and Engineering for light refreshments and a discussion lead by Dr. Jason Trelewicz of Stony Brook University.
The unique ability of grain boundaries to act as effective sinks for radiation damage plays a significant role in nanocrystalline materials due to their large interfacial area per unit volume. Leveraging this mechanism in the design of tungsten as a plasma-facing material, which will be subjected to high heat fluxes, elevated temperatures, aggressive particle and neutron fluxes, and high stresses, provides a potential pathway for enhancing its performance under fusion-relevant conditions. In this presentation, microstructure, phase evolution, and stability during self-ion irradiation is explored in nanocrystalline tungsten. Grain growth is shown to transpire through a discontinuous process at intermediate temperatures, which is coupled to an allotropic phase transformation of metastable β-tungsten to stable BCC α-tungsten. The addition of alloying elements stabilizes tungsten against the formation of this metastable phase while simultaneously inhibiting grain growth up to 1000°C. In situ self-ion irradiation also demonstrates that the addition of solute acts to stabilize the grain boundary network against irradiation-induced instabilities with insights into the underlying mechanisms presented from displacement cascade simulations. Nanoindentation results on helium implanted nanocrystalline tungsten will finally be summarized that reveal a new transition in the scaling of mechanical properties with fluence and attributed to the competition of softening due to grain boundary cavity formation with hardening from intragranular defect loop damage.
Department of Materials Science and Engineering