Sputtering rate of tungsten based high entropy alloys by light ions

Plasma-facing components and structural materials in fusion reactors must withstand high temperatures and intense radiation and particle fluxes. Tungsten-based high-entropy alloys (W-HEAs) possess numerous beneficial properties that make them promising candidates for nuclear applications. As plasma-facing materials, however, they are susceptible to erosion through sputtering driven by plasma-wall interactions, an undesirable phenomenon of significant concern in fusion research. Despite this, no experimental data on the sputtering yields of W-HEAs are currently available in the literature.

In this work, the sputtering of a thin W-HEA film by hydrogen, deuterium, and helium ions with energies ranging from 500 eV to 2 keV will be investigated. Thin films were employed to facilitate accurate analysis of material thickness before and after erosion, enabling precise determination of sputtering yields. The thin-film samples were synthesized on Si substrates via magnetron sputtering and subsequently irradiated using ions from an ion implanter. The elemental composition and thickness of the films were characterized using Ion Beam Analysis (IBA) methods, namely Rutherford Backscattering Spectrometry (RBS) and Time-of-Flight Elastic Recoil Detection Analysis (ToF-ERDA). Additionally, Medium Energy Ion Scattering (MEIS), which offers superior depth resolution compared to conventional IBA techniques, will be employed to investigate elemental segregation at the sputtered surface. Complementary Low Energy Ion Scattering (LEIS) measurements will be performed to probe the composition of the outermost atomic layer and assess sputtering-induced surface modifications with high surface sensitivity. Finally, the measured sputtering yields of the W-HEA are compared against those of its constituent elements reported in the literature, providing insight into whether alloying effects enhance or diminish erosion resistance relative to pure elemental targets.