Aluminium segregation profiles in the (110), (100) and (111) surface regions of the Fe 0.85 Al 0.15 random body-centered cubic alloy
Résumé
Thanks to a dedicated modelling of intensities, the depth sensitivity of X-ray photoemission is used to probe the segregation profile of aluminium at the (110), (100) and (111) low index surfaces of the body-centred Fe 0.85 Al 0.15 random alloy. Sputtered surface composition is close to the nominal bulk one, thus excluding preferential sputtering. Surface enrichment in aluminium upon annealing starts at around 700 K before reaching a stationary state above 1000 K. The average surface composition is close to Fe 0.5 Al 0.5 , corresponding to the B 2 CsCl structure on the phase diagram. The impacted depth, that is in the range of 2.5-3.5 nm, is quite significant. Although not evidenced previously in surface science conditions at FeAl single crystal surfaces, it is qualitatively in agreement with the segregation at grain boundaries and shear planes of Al-alloyed steels. This segregation tendency is rationalized through ab initio calculations.
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Dai et al. - 2019 - Aluminium segregation profiles in the (110), (100).pdf (1.3 Mo)
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