First-principles study from electronic structure to microstructure

Recent progress in theoretical calculations of phase stability, phase equilibria and transition dynamics based on the Cluster Variation Method (CVM) are reviewed. By combining CVM with electronic structure total energy calculations for a set of ordered compounds and the application of the Cluster Expansion Method, one is able to perform first-principles calculation of phase diagrams. Calculated L1₀-disorder transition temperatures for the Fe-Pd and Fe-Pt systems are in excellent agreement with experimental results. For the Fe-Ni system, the calculations predict the stability of a L1₀ ordered phase although it does not appear in the conventional phase diagram. The introduction of the CVM free energy into Phase Field equations enables one to perform multi-scale calculations covering atomistic and microstructural scales. By performing coarse graining operations, the gradient energy coefficient was derived from an atomistic point of view. The first-principles calculation of the time evolution of Anti Phase Boundary for the Fe-Pd system have been carried out and the results will be discussed. Finally, the CVM has been applied to the study of the crystal-glass (CG) transition. It is shown that the CG transition can be described in a coherent manner with order-disorder transition within the CVM and the Path Probability Method. This constitutes a first step towards the application of the CVM for the study of the CG transition.