Abstract
First reliable experimental oxygen diffusion coefficient data have been obtained in a Ti$_{48.3}$Al$_{47.7}$Cr$_{1.9}$Nb$_{2.1}$ near-γ GE alloy through secondary ion mass spectrometry (SIMS) depth profiling measurements of $^{18}$O isotopes between 500°C and 700°C. The following expression of diffusion coefficient D has thus been derived: D(m$^2$/s) =10$^{-10.6±1}$∙ exp(−107±10 kJ.mol$^{−1}$/RT). These data have been compared with theoretical calculations from literature, showing reasonable agreement concerning the activation energy, but significant discrepancy regarding the D values.