Atom Probe Tomography investigation of lithium uptake from liquid Pb-17Li by nanocrystalline/amorphous Al2O3 coatings.

Atom probe tomography has been applied to study lithium-induced corrosion of Pulsed-Laser Deposition grown Al 2 O 3 , which is a candidate coating material for breeder blankets for nuclear fusion reactors. Coated Eurofer97 specimens were immersed in static Pb-17Li for 7000 h with samples extracted from the regions near the ceramic-substrate interface to determine the extent of Li penetration. Li-enriched regions, which are non-stoichiometric with respect to any known equilibrium phases predicted by the Li-Al-O phase diagram at 823 K, are reported for the first time in Al 2 O 3. The nature and composition of the Li-enriched features were characterized with nanometre resolution. It was found that the Li content inside these features may increase to a maximum of 35 at%, with the adjacent Al 2 O 3 matrix containing approximately 5–10 at% Li. Based on these results, the corrosion mechanism of amorphous Al 2 O 3 is proposed to be Li substitution of Al atoms. • The near-interface region of the alumina barrier coating on a fusion steel was extracted by focused ion beam milling. • The distribution of Li atoms intruding into an alumina coating is imaged for the first time with atom probe tomography. • Nanoscale region significantly enriched in Li were observed near the ceramic-metal interface. • Their compositions were identified as non-stoichiometric and implied these are non-equilibrium microstructural features. • A possible lithiation mechanism for amorphous alumina was proposed based on composition of the clusters. [ABSTRACT FROM AUTHOR]