Analysis of shape, orientation and interface properties of Mo2C precipitates in Fe using ab-initio and finite element method calculations

We study the Mo2C precipitate, a carbide commonly used for secondary hardening in steels, and its interface to the Fe matrix using a combination of ab-initio density functional theory and finite element simulations. For Mo2C and Fe, the elastic properties as a function of temperature are determined and different interfaces of the carbide to the matrix are characterized. With finite element simulations that use the derived elastic properties and interface energies as input, the energy contributions from elasticity and creep are evaluated. Combining the results from atomic to micro scale allows to explain the specific needle shape of these precipitates that has been reported experimentally. For one selected interface, also the full elastic properties are determined with ab-initio methods and compared to the GrimsditchNizzoli approach, where we find good agreement. Our study shows how a combination of the ab-initio and the finite element method may be used to characterize and understand the micro-mechanical effects of precipitates. (c) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.