First-principles study of thermodynamic properties and solubility of aluminum-rare-earth intermetallics

Thermal properties of several L12 Al3RE (RE = Y, Dy, Ho, Er, Tm and Lu) intermetallic compounds are studied using the first-principles phonon calculations. The thermal expansions, the heat capacities at constant pressure, and the isothermal bulk modulus at finite temperatures are obtained from the quasiharmonic approximation. Based on thermodynamic properties, we calculate the solubility of RE elements in Al. We find that the solubility limits increase when the atomic number of RE element decreases from Lu to Y. Dy and Y have the low price and high solubility limits, adding Dy and Y to Al–Sc alloys can reduce the production costs of Al-based alloys. It is meanwhile, Y and Dy have high strengthening capability and much better oxidation resistance, and they are probably the better candidates as potential additions to dilute Al–Sc alloys among several RE elements investigated.