Beschreibung:
Ir 3 Z ( Z = Ti, V, Zr, Nb, Hf and Ta) ultra-high temperature alloys, well known as their super high melting point and excellent mechanical properties, are promising candidates for high temperature structural materials beyond nickel-based materials. Nevertheless, knowledge of their mechanical properties and the mechanism of tensile/shear deformation still remains poor. In this work, the fundamental mechanical properties and the mechanical behavior under different tensile/shear loading directions of Ir 3 Z alloys were studied using DFT calculations. All Ir 3 Z alloys have very high mechanical modulus (404.7~561.3GPa for Young’s modulus). For both mechanical and tensile/shear strength, Ir 3 V, Ir 3 Nb and Ir 3 Ta are distinctly superior to Ir 3 Ti, Ir 3 Zr and Ir 3 Hf, in which Ir 3 V shows the most outstanding performance. Furthermore, these alloys exhibit similar tensile/shear stress-strain relationship and all of them show anisotropic mechanical behavior under strain, i.e., [100] direction shows the strongest resistance to tensile stress and (111)/[10] slip system turns out to be the most likely slip surface. Meanwhile, the results of average charge density as well as the density of states diagram suggest that the degree of interatomic bonding mainly determines the ideal strength of different structure and tensile/shear direction of Ir 3 Z alloys