Correlation between lattice-strain energetics and melting properties: Molecular dynamics and lattice dynamics using EAM models of Al

摘要

We report the results of investigation into correlations between the melting behavior and the energetics as a function of lattice strains using the concepts of the Bain path, the physically allowed lattice-invariant strain, and the generalized stacking fault surface, within the framework of empirical descriptions. We choose aluminum systems for the investigation, as a typical example of metallic systems. The elastic properties, vibrational properties, and thermodynamic properties in various situations are calculated using the harmonic-approximation analyses and molecular-dynamics simulations based on the embedded-atom-method potentials. We discuss the relations of the melting properties with elasticity, energetics, and phonon instabilities found in the adopted schemes. The search of energetics and phonon instabilities along these paths are found to be a useful procedure for approximately obtaining the melting points, for comparing the transferability among interatomic potentials proposed, and even for understanding lattice-defect formation properties. We also report on Richard's rule found among the interaction models adopted. Since there is a possibility that trends of material properties can be understood without actually evaluating the associated physical values, energetics, and instabilities along these paths might also be useful information for material designs in mechanical and/or high-temperature properties.