Molecular Dynamics Investigation of the Effect of Lanthanum on the Diffusivity of Niobium in Austenite

Abstract

By employing the force-matching method, an embedded-atom-method potential for FeNbLa dilute solid solution has been constructed by fitting to a set of density-functional theory (DFT) data of reference structures. The developed potential reproduces the properties of the reference structures in good agreement. Using the developed potential, molecular dynamics simulations were performed to investigate the diffusion coefficients of Nb in FeNb and FeNbLa systems, respectively. The results indicate that the addition of La suppresses the diffusion of Nb in fcc Fe, the activation energy of Nb was determined to be 47551 J/mol in the absence of La while 82672 J/mol in the presence of La, and consequently leads to the longer incubation time of NbC precipitation in the La micro-alloyed austenite.