CSUDDCC1—A diffusion database for multicomponent cemented carbides

Abstract

Cemented carbides are hard and tough materials for cutting tool, consisting of micrometer-sized carbides embedded in a ductile metal binder phase. In order to increase the performance and extend the service lifetime of the cemented carbides, graded cemented carbides have been developed. The formation of gradient zone during liquid phase sintering is a diffusion-controlled process, and knowledge of diffusivity is indispensable to understand formation mechanism, optimize technological parameters and design a new type of graded cemented carbides. In this paper, a diffusion database for multi-component C–Co–Cr–W–Ta–Ti–Nb–N cemented carbides has been developed through a combination of experiment, theoretical analysis and assessment. The diffusion database contains the atomic mobility parameters for different diffusing elements in liquid and fcc phase. The atomic mobility parameters in liquid phase 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. In conjunction with the thermodynamic database for cemented carbides (CSUTDCC1: Central South University Thermodynamic Database for Cemented Carbides—version-1), the diffusion database (CSUDDCC1: Central South University Diffusion Database for Cemented Carbides—version-1) can be used to simulate the gradient sintering process. Simulations of different kinds of graded cemented carbides are presented using the databases and compared where possible against experimental data, in order to validate its accuracy.