Computational study of mechanical properties in βCu−Al−Zn

Abstract

The mechanical properties of the bcc β phase in Cu−Al−Zn alloys are investigated by means of first-principles calculations. Several bcc-based superstructures are considered, with compositions along three different lines. Elastic constants, Young´s and shear moduli, Zener´s anisotropy, sound velocities and Debye temperatures are determined and analyzed as a function of composition. The calculated results are compared with the available experimental data, and general trends are identified. For the line of compositions with electron concentration e/a=1.5 (Cu3Al to CuZn line), a decrease of the elastic constants with the Zn content is obtained. Elastic constants for this line are in the range C11≈ 120?140 GPa, C12≈ 110?130 GPa and C44≈ 85?100 GPa, in general good agreement with the experiment. Values of the anisotropy and Debye temperatures are also comparable with the measured ones.