Crystallographic analysis of nano-tendril bundle vs fuzz growth on tungsten exposed to helicon wave-coupled helium plasma

The propensity for nano-tendril bundle (NTB) vs widespread nano-tendril growth (i.e., fuzz) on polycrystalline W under varying ion energy modulation conditions, from DC to peak-to-peak energy modulation of 42 eV at 13.56 MHz, is correlated with the crystal orientation of the underlying grains. Grains that are vicinal to crystal orientations with high surface diffusivity (e.g., {101} for a body centered cubic crystal structure) exhibit NTB growth at lower ion energy modulation amplitude than grains that are vicinal to low surface diffusivity orientations, such as {100}. Adatom mobility considerations are presented to describe the experimental observations. These results support that surface diffusion or W adatom mobility enhanced by ion bombardment plays a key role in the surface morphology evolution of W under He irradiation

Mechanical and microstructural response of the Al0.5CoCrFeNi high entropy alloy to Si and Ni ion irradiation

© 2020 The Authors The nearly infinite compositional design space of high entropy alloys (HEAs) presents many opportunities to improve performance in extreme environments, particularly for nuclear reactors. The ability of some HEAs to resist high amounts of radiation damage, while well documented, has not yet been fully exploited. We studied the irradiation effect of different ions (Si and Ni) on the microstructure and mechanical properties of the Al0.5CoCrFeNi alloy at its equilibrium state, and of the individual response of each phase to irradiation. The results show a stronger effect of Si ions and differences in response of the ductile FCC (A1) and brittle ordered BCC (B2) phases towards irradiation. This finding highlights the need to further probe unexplored compositional spaces in HEAs, as further optimization is likely to yield further compositional and microstructural stability with practical applications