FIRST-PRINCIPLES INVESTIGATION OF THE THERMODYNAMICS PROPERTIES OF Al 3 Sc AND Al 3 Zr INTERMETALLICS

Abstract

A first-principles investigation of the structural and thermodynamic properties of Al3Sc and Al3Zr intermetallics has been conducted using the norm-conserving pseudopotentials within the local density approximation in the frame of the density functional theory (DFT) and the density functional perturbation theory (DFPT) with the ABINIT code. The calculated formation enthalpy and cohesive energy results show that both phases have strong alloying ability and Al3Zr has a higher structural stability than Al3Sc phase. By means of calculations, the relationships of the vibrational free energy constant-volume specific heats entropy bulk modulus and thermal expansion with the elevated temperatures are given. The calculated bulk modulus indicates that Al3Sc and Al3Zr phases can improve the high-temperature creep resistance properties of aluminum alloys. The calculated datum of the thermal expansion and the diffusion speed of Sc and Zr in Al can explain the mechanism that the solder wire with Sc and Zr can improve the strength of welding gap and the resistance ability of hot crack.