First-principles study of structural, elastic and electronic properties of ZrIr alloy

The structural, elastic and electronic properties of ZrIr alloy with the B2, B19′, FeB, CrB and ZrIr structures have been investigated by the first-principles calculations based on density functional theory. It is found that the lattice constants of the B2 and ZrIr phases agree well with the corresponding experimental data. The predicted phase stability trend is ZrIr > FeB > CrB > B19′ > B2 from the calculated formation energy and density of states. The independent elastic constants are calculated, indicating that the FeB, CrB and ZrIr structures are mechanically stable except for the B2 and B19′ structures. Elastic properties such as the bulk modulus B, shear modulus G, Young's modulus E and Poisson's ratio ν for polycrystalline crystal of the FeB, CrB and ZrIr structures have been calculated from the independent single-crystal elastic constants by using the Voigt-Reuss-Hill approximation. By analyzing the ratio between the bulk and shear modulus, it is confirmed that the FeB, CrB and ZrIr structures exhibit a good ductile property. Our calculations show that the stronger hybridization between Zr d and Ir d states is responsible for the phase stability of the ZrIr structure.