First-Principle Study On Electronic And Mechanical Properties For Multiple Al-Based Intermetallics

Aluminum alloys, as a familiar structural material, are widely used in the field of defense, aerospace, marine and automotive manufacturing due to their low cost, light weight and high performance. But the most serious weakness of them is the brittleness. Therefore, they have focused altitudinal attention of researchers to improve their mechanical properties. First-principles method based on density functional theory(DFT) has made it possible to study the electronic structures and mechanical properties of solids simplistically. This paper mainly investigated the electronic structures and mechanical properties of Al-based intermetallic compounds, more details are as follows:1.Electronic structure, mechanical properties and work function of Al-based intermetallic compounds with different content of Ti(AlCu3, AlCu2 Ti and AlTi3) are investigated by using first-principles method. Our calculated lattice constants agree well with the experimental data. Effects of different Ti content on the electronic structures and mechanical properties of Al-based intermetallics are further analyzed and discussed in view of the density of states and charge density. Since the decreasing of cohesive energy has been observed when Ti content increases, work function calculations present the same tendency. Moreover, the ratio of the bulk modulus to shear modulus was calculated to account for good ductility of these three crystals and we obtained that AlCu3 has the best ductility. Finally, our results of DOS indicate that AlTi3 has the most intense chemical bonds among these three Al-based intermetallics because of its strongest hybridization. This is a disadvantage for its ductility. Charge density distributions also provide an evident of the strong binding in AlTi3.2. Electronic structure and mechanical properties of Al-based intermetallic compounds with defect are investigated by using first-principles method. Formation energy shows that Al4Cu8Zr3 is more stable. Moreover, the ratio of the bulk modulus to shear modulus was calculated to account for good ductility of these three crystals and we obtained that Al4Cu8Ti3 has the best ductility. Finally, our results of DOS indicate that Al4Cu8Zr3 has the most intense chemical bonds among these three Al-based intermetallics because of its strongest hybridization. This is a disadvantage for its ductility.