CSUDDCC2: An Updated Diffusion Database for Cemented Carbides

Cemented carbides are widely used in industry as cutting tools, wear parts, as a result of the high hardness and good toughness. A reliable diffusion database is critical to simulate microstructure evolution of cemented carbides. In 2014, we established version one of CSUDDCC1 (Central South University Diffusion Database for Cemented Carbides Version one). In this work, a description for the updated diffusion database CSUDDCC2 is presented. The atomic mobility database for fcc and liquid in C–W–Co–Fe–Ni–Cr–V–Ti–Ta–Nb–Zr–Mo–Al–N cemented carbides was established based on our new experimental data, literature data, first-principles calculation and theoretical assessment via the DICTRA (Diffusion Controlled TRAnsformation) software package. The atomic mobility parameters in liquid are theoretically calculated by the newly modified Sutherland equation, and the atomic mobility parameters in fcc phase are optimized by the diffusivities measured in the present work and from the literature. The mobility parameters for self-diffusion and impurity diffusion in metastable fcc structure were determined through a semi-empirical method or first-principles calculations. Comprehensive comparisons between calculated and measured diffusivities indicate that most of the experimental data can be well reproduced by the currently obtained atomic mobilities. Combining the thermodynamic database for cemented carbides, the diffusion database has been used to simulate the microstructure evolution during sintering of gradient cemented carbides. The simulated microstructure agrees reasonably with the experimentally observations.