Reinvestigation of the Bulk Modulus for fcc Al using a Helmholtz Energy Approach

While extensive studies on the bulk modulus of fcc Al have been conducted, there still exist controversies regarding to the experimental values. In the present work, we adopted a Helmholtz energy approach based on the Morse function, the free electron Fermi gas model, as well as a modified Debye–Grüneisen model ensuring intrinsic thermodynamic relationship satisfied. To identify consistent bulk modulus data, all the model parameters for fcc Al were evaluated by using comprehensively available experimental data on heat capacity, elastic modulus, thermal expansivity, molar volume, etc., over wide temperature and pressure ranges. Reasonable agreements have been achieved in this work without inconsistency among various thermodynamic and thermophysical properties. Our calculated bulk modulus of fcc Al agrees well with the data reported by Kamm and Alers, Gerlich and Fisher, Ho and Ruoff and the assessment done by Wang and Reeber. However, it is impossible to reconcile the parameters to fit the recent data from Raju et al., as well as the results from Tallon and Wolfenden due to the intrinsic thermodynamic constraints.