Atomistic simulation of self-diffusion in bcc metals: Mo and Fe

Daria Smirnova, Interdisciplinary Centre for Advanced Materials Simulation (ICAMS), Ruhr-University, Bochum, Germany
Sergei Starikov, Interdisciplinary Centre for Advanced Materials Simulation (ICAMS), Ruhr-University, Bochum, Germany
Yanyan Liang, Interdisciplinary Centre for Advanced Materials Simulation (ICAMS), Ruhr-University, Bochum, Germany
Matous Mrovec, Interdisciplinary Centre for Advanced Materials Simulation (ICAMS), Ruhr-University, Bochum, Germany
Ralf Drautz, Interdisciplinary Centre for Advanced Materials Simulation (ICAMS), Ruhr-University, Bochum, Germany

One of the prominent ways for the theoretical study of self-diffusion in metals is atomistic simulations, i.e. first-principle calculations and classical molecular dynamics. In this work, we apply these methods to consider the nature of self-diffusion in two different bcc metals: molybdenum and iron. Here we apply atomistic simulations methods to perform detailed study of the characteristics that determine the value of self-diffusion coefficient from zero temperature up to the melting point. We considered vacancy diffusivities, vacancy formation and migration energies, and vacancy formation entropies. We also carried out molecular dynamics simulations that allow direct observation for the process of self-diffusion at the atomic scale. For molybdenum, all calculations are done with three different interatomic potentials, and the differences between simulation results are analyzed and compared with the experimental points. The same formalism is also applied for the bcc Fe. The mechanism of the vacancy diffusion in iron is studied with three different interatomic potentials available for Fe, and the results are compared with the existing experimental data. Such calculations allows to get an insight into the diffusion mechanisms existing in the chosen metals, and also, helps to chose an appropriate model settings for the diffusion simulations.

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