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

Abstract

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