Single-phase interdiffusion in TiAl and Ti3Al intermetallic compounds

Interdiffusion in single-phase diffusion couples of TiAl and Ti3Al has been investigated over the temperature range of 1118 to 1583 K. Concentration distributions after annealing were measured by an electron probe microanalyzer (EPMA). Interdiffusion coefficients were calculated according to the Boltzmann-Matano method. No significant concentration dependence of the interdiffusivities in both compounds was detected. The temperature dependence of the diffusivities follows Arrhenius laws with a pre-exponential factor D0 = 2.8 × 10−4 m2 s−1 and an activation enthalpy Q = (295 ± 10) kJ mol−1 for TiAl, and D0 = 1 × 10−3 m2 s−1 and Q = (312 ± 6) kJ mol−1 for Ti3Al, respectively. The present results are discussed together with Ti self-diffusion data for TiAl and Ti3Al from tracer-diffusion experiments.