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Abstract: Density functional theory based ab- initio total energy calculations are used to determine the concentration dependences of equilibrium lattice parameters, densities, mixing energies (phase stability) and elastic constants of binary random Mg1−x Li x alloys spanning the entire concentration range, in the HCP, FCC and BCC structures. A model for predicting phase stability and elastic properties of random alloys is proposed. The current model is applied to binary Mg–Li system as a test study. The predicted phase stability trends at 0 K resemble those observed experimentally in Mg–Li phase diagram, more especially at lower temperatures. The proposed model for random alloys is not only accurate but also less computationally expensive compared to traditional supercell approach. [Copyright &y& Elsevier]

Abstract: The first principles pseudopotential calculations based on the Perdew–Burke–Ernzerhof (PBE) form of generalized gradient approximation (GGA) within density functional theory (DFT) have been utilized to investigate the structural and elastic properties of cubic-based Mg–Li alloys. The heats of formation and elastic moduli were used in predicting structural stability profile, and their results are consistent with each other. In terms of phase stability, an interesting correlation between the calculated tetragonal shear modulus (C′) and formation energy of corresponding bcc and fcc ordered compounds relative to hcp Mg and Li lattices is drawn. The predicted stability trend due to structural energy difference was further confirmed by electronic structure calculations based on Jones-type analysis. [Copyright &y& Elsevier]

Abstract: We investigated the phase stability from B2 to L10/B19/B19′ in equiatomic PtTi alloy using the density functional theory within the generalized gradient approximation. Their structural, energetic, electronic and the mechanical properties were determined to show the stability trend of the shape memory binary alloy. The lattice parameters are well reproduced and agree to within 2% with the available experimental data. We found that the calculated heats of formation and density of states predicted B19 and B19′ PtTi to be the most stable structures compared to B2 and L10. On the other hand, their mechanical stability predictions show consistency with regard to the elastic constants and phonon dispersion curves. The elastic instability (negative C ij) and soft modes were observed in the B2, B19 and B19′ structures and not found in the L10 structure. [Copyright &y& Elsevier]