Development of a diffusion mobility database for Ni-base superalloys

For the fcc phase of the Ni-Al-Co-Cr-Hf-Mo-Re-Ta-Ti-W system, diffusion data in various constituent binary systems were assessed to establish a multicomponent diffusion mobility database. The diffusion assessment relied on an existing thermodynamic database for the calculation of needed thermodynamic factors. The mobilities determined for the self-diffusion of the components in the fcc phase (a metastable state for some components) were consistent with the correlation of the diffusivity with the melting point. The general agreement of calculated and measured diffusion coefficients in the Ni-Co-Cr-Mo and Ni-Al-Cr-Mo quaternary systems demonstrated the ability of the database to extrapolate to higher order systems. Finally, the mobility database, in conjunction with an available thermodynamic database and a finite-difference diffusion code. was used to simulate a multicomponent diffusion couple between two commercial Ni-base superalloys. (C) 2002 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved.