Modeling the diffusion-controlled phase transformations in transition metal carbide multilayer composites

Abstract

The kinetics of the carbon-diffusion-controlled Me/MeC phase transformation in transition metal carbide metal ceramic multilayer composites were investigated using mesoscale and continuum level modeling. To track the metal-ceramic interface the phase transformation was modeled as a Stephan problem wherein the interface was treated as a moving boundary controlled by the bulk and interfacial diffusion of carbon. Simulations were allowed to continue until the disappearance of the metal layers whereupon an effective diffusivity relating the bilayer width, transformation time, and temperature was calculated. The effective diffusivity data was subsequently used to develop a coarse-grained model capable of predicting phase transformation characteristics and providing valuable insight into the parameters that control the phase transformation.