Surface modification and sputtering of FeCrAl alloys exposed to low-energy hydrogen plasmas

Abstract

In the present paper processes of sputtering and surface modification of commercial and experimental FeCrAl composites alloyed with yttrium, molybdenum and zirconium were investigated. Using a field-emission scanning electron microscope, it was shown that under the influence of low-energy (500 eV) hydrogen plasma with a flux about 3.2 ⋅ 1020 m–2 ⋅ s–1 and fluence 4 ⋅ 1024 m–2 at Troom, surface morphology develops due to the formation of grooves along grain boundaries, macro- and microcracks, as well as intragranular pits due to the sputtering of precipitates. Determination of the composition of precipitates by an energy dispersive X-ray spectrometer allowed to establish that aluminum oxide is preferentially distributed in the grains of FeCrAl-based alloys, and yttrium oxides are localized along grain boundaries. Results of erosion studies indicated that the sputtering yields for hydrogen on all alloys are 1.05– 0.38 at./ion and doesn’t exceed those for published data for pure iron and chromium. For experimental alloys doped with yttrium and molybdenum found that the obtained sputtering coefficients were in several times lower than for steel SS304 and only one and a half times higher compared to tungsten.