Reviews on Modeling of Diffusion-Induced Mass Transportation in Functionally Graded Cemented Carbides

Abstract

Graded sintering is the fundamental process of fabricating functionally gradient cemented carbide (FGCC). The diffusion-induced mass transport in cemented carbide can result in the formation of gradient microstructure and thusly lead to gradual changes in micro property. So far, several types of FGCC have been developed, and the factors that can influence the gradient formation are complex. Section 2 introduces the process of forming diffusion-controlled near-surface layer in WC-Ti (C,N)-Co hardmetal as well as the kinetic modeling work that reveals the key factors for the layer formation. Section 3 reviews the dual properties carbide produced under carburization atmosphere, for which the carbon content is a main factor of the gradient thickness. There are two models describing this process, representing different mass-transport mechanism of the so-called liquid phase migration (LPM) process. In section 4, previous and new results of modeling LPM in different dimensions and scales are presented, and the diffusion-controlled nature of LPM are discussed.