Oxygen Diffusion Coefficient in the γ Phase of a Tial GE Alloy Determined by SIMS

First reliable experimental oxygen diffusion coefficient data have been obtained in a Ti_48.3Al_47.7Cr_1.9Nb_2.1 near-γ GE alloy through secondary ion mass spectrometry (SIMS) depth profiling measurements of ¹⁸O isotopes between 500°C and 700°C. The following expression of diffusion coefficient D has thus been derived: D(m²/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.