Phase stability and anisotropic elastic properties of the Hf-Al intermetallics: A DFT calculation

The first-principles calculations based on density-functional theory were performed to investigate the structural properties, phase stability, and elastic properties of several selected Hf-Al intermetallics. The calculated formation enthalpies show that HfAl2 is the most stable in these intermetallics. The predicted elastic moduli results indicate that the order in the degree of elastic anisotropy is HfAl > Hf2Al > D0(22)-HfAl3 > Hf3Al2 > Hf5Al3 > Hf2Al3 > D0(23)-HfAl3 > Ll(2)-HfAl3 > Hf4Al3 > HfAl2. By using the procedure of Brugger, the calculated sound velocities in different directions for the Hf-Al intermetallics are anisotropic. The Debye temperatures were also estimated from the elastic constant evaluations of Hf-Al intermetallics. (C) 2015 Elsevier B.V. All rights reserved.