First-principles studies on phase stability, anisotropic elastic and electronic properties of Al-La binary system intermetallic compounds

Abstract

The excellent comprehensive properties of Al-La binary alloy are mainly due to the stable distribution of Al-La intermetallic compounds in the microstructure. In this work, first-principle calculations have been performed to investigate the phase stability, elastic and electronic properties of eight binary Al-La intermetallic compounds. The results indicated that crystal parameters of Al-La compounds agree well with other experimental and calculated values. The calculated formation enthalpy and cohesion energies of these compounds are less than zero, which indicates that these Al-La binary compounds have good thermal stability. The result reveals that the cohesive energy of these Al-La intermetallic compounds in the binary system decreases with the increase of La content. Among these compounds, Al3La has the highest shear modulus and the strongest resistance to shear strain. The result indicates that the Al-La compounds in this study have an intrinsic sixth power correlation with the work function. It is found that Al11La3 is the most anisotropic in these Al-La binary compounds. The value at the Fermi level is not equal to zero, indicating that all these binary compounds have metal properties. Debye temperature calculation results show that Al3La has the strongest binding force between atoms of Al-La intermetallic compounds. Furthermore, the results show that these compounds have anisotropy of longitudinal and transverse sound velocity in different crystallographic directions.