Single-phase interdiffusion in Ni3Al

Interdiffusion experiments have been made using single-phase diffusion couples of Ni3Al over the temperature range from 1223 to 1473 K. The interdiffusion coefficient has been obtained from the concentration profiles measured by electron-probe microanalysis. The interdiffusion coefficient, (D) over tilde, is 4-8 times larger than the tracer-diffusion coefficient of Ni, D-Ni*, and increases with increasing Al concentration. For the stoichiometric composition, it is expressed as (D) over tilde = 10-2.6+/-0.7 exp(-305 +/- 17 kJ/mol/RT) m(2)/s. reported in the literature and the thermodynamic factor evaluated from experimental data of the thus estimated is smaller by a factor of 3-4 at 1400 K than thermodynamic activity. The magnitude of D-Al* that of D-Ni* in the temperature range examined. For example, D-Al* approximate to (0.25 - 0.38)D-Ni* at 1400 K. (C) 1998 Acta Metallurgica Inc. Published by Elsevier Science Ltd. All rights reserved.