Molecular Dynamics virtual testing of thermally aged Fe-Cu microstructures obtained from multiscale simulations

Virtual nano-tensile tests using Molecular Dynamics (MD) simulations are performed in order to predict the change in mechanical strength of Cu-alloyed α-Fe with thermal ageing. A novel sequential multiscale approach is adopted to simulate the microstructure evolution during ageing. In this approach, kinetic Monte-Carlo simulations are used to capture nucleation, growth and early stages of Cu particle coarsening whereas phase-field simulations capture further particle coarsening yielding particle mean radii of above 3 nm in feasible computation times. The MD results show the correctness of this multiscale approach by predicting a continuous trend in structure-property correlation. The yield strengths of the samples are found to decrease with ongoing thermal ageing due to the lack of a priori existing dislocations in the material and the enhanced dislocation nucleation at Fe-Cu interfaces.