First-principles calculations to investigate the anisotropic elasticity and thermodynamic properties of FeAl3 under pressure effect

Abstract

We have employed the first-principles calculations and quasi-harmonic Debye model to investigate the effect of the pressure on anisotropic elasticity and thermodynamic properties of FeAl3. According to Christoffel’s equation, the wave velocity anisotropy of FeAl3 as a function of pressure was also studied. Based on 3D surfaces and 2D projection contours, the anisotropy of shear modulus for FeAl3 changes significantly with the increasing pressure, and increases more obviously on [001] direction than that on [100] direction under high pressure. The thermodynamic properties calculations show that the volume of FeAl3 decreases with the increasing temperature and pressure. The bulk modulus decreases with the increasing temperature, and increases with the increasing pressure. On the contrary, the thermal expansion coefficient, the heat capacities, and Grüneisen constant increase with the increasing temperature, and decrease as pressure increases. It is found that the bulk modulus and Grüneisen constant display strong pressure dependence, while the heat capacities are sensitive to the temperature. And the thermal expansion coefficient is affected simultaneously by the pressure and temperature.

Keywords

• FeAl3
• Anisotropic elasticity
• Thermodynamic properties
• Pressure
• First-principles