Mechanical Properties Evaluation of Zr Addition in L12-Al3(Sc1-x Zr x ) Using First-Principles Calculation

L1(2)-Al-3(Sc1-x Zr (x) ) can be used as a grain refiner and recrystallization inhibitor in forming and heat-treatment of wrought aluminum alloy. In this work, the mechanical properties of L1(2)-Al-3(Sc1-x Zr (x) ) (0 < x < 0.5) have been systematically evaluated using first principles calculations. The optimized structural parameters obtained through the virtual crystal approximation were in good agreement with available experimental and calculated data. The computed bulk modulus of L1(2)-Al-3(Sc1-x Zr (x) ) increased while the shear modulus and Young's modulus decreased with increasing Zr addition. The ductility of L1(2)-Al-3(Sc1-x Zr (x) ) estimated by Pugh empirical criterion and Cauchy pressure were improved with Zr addition. The calculated ideal strength of L1(2)-Al-3(Sc1-x Zr (x) ) along the [001], [110] and directions increased linearly with Zr additions. The addition of Zr gave great improvements in the ideal strength along the [110] direction and the ductility in the [001] direction, respectively. The calculated electronic density of states and the charge density distribution revealed that the valence electron increased with Zr addition and hence strengthened the p-d covalent bonding and d-d bonding, resulting in the improvements in ideal strength and ductility. The evaluation data would be useful in materials design and process optimization for Al alloys in forming and heat treatment.