Esfuerzo triaxial ideal de Ti, Zr y Hf con estructura <span style="font-style:italic">fcc</span>: un estudio de primeros principios

Abstract

At room temperature and zero pressure Ti, Zr and Hf crystallize in the hexagonal close-packed phase. Recent reports have shown that these elements are elastically metastable [14] in the structure face-centered cubic (fcc). We present the ideal triaxial strength of Ti, Zr and Hf metals with fcc structure, obtained by first principles calculations using the Density Functional Theory. It was used the Generalized Gradient Approximation and Local Density Approximation for exchange-correlation energy and the electron-nucleus interaction we use pseudopotentials. From the calculation of total energy for each element were obtained lattice parameters, bulk, shear and Young modulus, as well as elastic constants in the absence of stress and as a function of applied stress. In the ground state, we obtain good agreement in lattice parameters and elastic constants with experimental data. From the Born-Wang criteria we studied the ideal mechanical resistance to compression of each element. The maximum values of the stress (15, 13.5 and 22.8 GPa for Ti, Zr and Hf, respectively) are explained in terms of the density of states and charge density at the Fermi level.