Thermodynamics of Al3Li nano-clusters in an Aluminum solid solution

An accurate thermodynamic description of nano-clusters in a solid solution is a pre-requisite for a reliable predictive homogeneous nucleation model. Unfortunately, the classical textbook description which consists in describing the free energy as a sum of a volume energy part and a surface energy parts with constant interface energy fails to capture the thermodynamic of small clusters at high enough temperatures. Equilibrium Monte Carlo (MC) calculations have been performed to study the free energy of Al3Li clusters as a function of size and temperature. Constant first and second nearest neighbor interactions were used as input. Calculations show that for a temperature range between 0 degrees C and 200 degrees C, the simplistic textbook description fails to reproduce the free energy of Al3Li nanoclusters and that a more complex description is required to reproduce MC results and to capture the cluster conformation entropy. This study is part of a modeling project on the simulation of the microstructure of AIRWARE (TM) alloys.