Rofiques Salehin¹, Xiaochuan Tang¹, Gregory Thompson², Christopher R. Weinberger¹; ¹Colorado State University, ²University of Alabama

Mass transport in the transition metal carbides can is complicated because these materials are strongly nonstoichiometric and exhibit both metallic and covalent bonding. Furthermore, mass transport is a critical property in these materials as they are used as structural materials at extreme temperatures and regularly subjected to creep loading. To provide an understanding of mass transport and creep in these materials we combine density functional theory, cluster expansion methods, Monte Carlo and kinetic Monte Carlo to explore how the carbon and metal atoms diffuse. Specifically, we compute the formation and migration energies of a wide range of defect complexes in these materials from DFT and extend them to larger scales with cluster expansion and Monte Carlo methods. Our results show that in the group IVB carbides the main mechanism is through a coordinated vacancy cluster migration method while in the VB carbides the vacancy migration is typically uncoordinated.