Development of a Diffusion Mobility Database for Ni-Base Superalloys
Carelyn E. Campbell, William J. Boettinger, Ursula R. Kattner
For a wide variety of Ni-base superalloy applications, including solidification, homogenization, y precipitation, bonding and repairing processes, and protective bond coats, multicomponent diffusion data are needed. Thus, in the Ni-Al-Co-Cr-Hf-Mo-Re-Ta-Ti-W system, diffusion data in the various binary and ternary systems were assessed for the fcc phase. These assessments were combined with data from various assessment in the literature to develop a diffusion mobility database. The diffusion assessments relied on existing thermodynamic databases for the calculation of needed thermodynamic factors. Evaluation of the current assessment work employed the well-known diffusion correlation that the diffusivity at the melting temperature is relatively constant for pure metals. Comparison calculated and measured diffusion coefficients in the Ni-Co-Cr-Mo and Ni-Al-Cr-Mo 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 CMSX-4 and Rene-N4.