Aluminium-26 grain boundary diffusion in pure and Y-doped polycrystalline α-alumina

Aluminium grain boundary diffusivities were measured in pure and Y-doped polycrystalline alpha-Al2O3 using the artificial aluminium isotope Al-26 as a tracer. An advanced preparation technique for the Al-26 tracer source enabled secondary ion mass spectrometry (SIMS) measurements to analyse the Al-2 depth distributions in the polycrystalline materials. Simultaneously performed O-18 and (26)AI tracer diffusion experiments demonstrated clearly in the most direct way that Al-26 grain boundary diffusion is significantly faster than O-18 grain boundary diffusion. There was no significant difference in aluminium grain boundary diffusivities in pure and Y-doped polycrystalline alpha-Al2O3. The experimental results of this work imply that diffusion creep in alumina is unlikely to be controlled by Al grain boundary diffusion. (C) 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.