Atomistic origin of the thermodynamic activation energy for self-diffusion and order-order relaxation in intermetallic compounds II: Monte Carlo simulation of B2-ordering binaries

Abstract

The validity of previously derived formulae expressing the activation energies for self-diffusion and ‘order–order’ relaxations in intermetallics in terms of the activation energies of more elementary processes involved in the phenomena is tested by simulation of particular binary systems. The simulation results were in good agreement with the tested formulae. It was shown that the relationship between the activation energies observed in triple-defect B2-ordering binaries, where the value of the activation energy for order–order relaxations is substantially lower than that for self-diffusion, does not hold in the case of non-triple-defect binaries. Using the tested formulae, the origin of the effect was elucidated and attributed to the atomistic origin of the tendency for triple-defect disordering.

Keywords:

• Diffusion
• relaxation
• intermetallics
• Monte Carlo simulations

Acknowledgement

Access to the computation facilities at the ACK Cyfronet AGH, Krakow (supercomputer Prometheus) is greatly appreciated.