First-Principles Investigation of Phase Stability, Elastic and Thermodynamic Properties in L1 2 Co 3 (Al,Mo,Ta) Phase
TL;DR: In this paper, the phase stability, elastic, and thermodynamic properties of polycrystalline Co3(Al,Mo,Ta) with the L12 structure were investigated using the Voigt-Reuss-Hill approach.
Abstract: First-principles calculations have been performed to investigate the phase stability, elastic, and thermodynamic properties of Co3(Al,Mo,Ta) with the L12 structure. Calculated elastic constants showed that Co3(Al,Mo,Ta) is mechanically stable and possesses intrinsic ductility. Young’s and shear moduli of polycrystalline Co3(Al,Mo,Ta) were calculated using the Voigt-Reuss-Hill approach. It was found that the shear and Young’s moduli of Co3(Al,Mo,Ta) were smaller than those of Co3(Al,W). States density indicated the existence of covalent-like bonding in Co3(Al,Mo,Ta). Temperature-dependent thermodynamic properties of Co3(Al,Mo,Ta) could be described satisfactorily using the Debye-Gruneisen approach, including entropy, enthalpy, heat capacity and linear thermal expansion coefficient, showing their significant temperature dependences. Furthermore the obtained data could be employed in the modeling of thermodynamic and mechanical properties of Co-based alloys to enable the design of high temperature alloys.
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01 Jan 2005
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TL;DR: A simple derivation of a simple GGA is presented, in which all parameters (other than those in LSD) are fundamental constants, and only general features of the detailed construction underlying the Perdew-Wang 1991 (PW91) GGA are invoked.
Abstract: Generalized gradient approximations (GGA’s) for the exchange-correlation energy improve upon the local spin density (LSD) description of atoms, molecules, and solids. We present a simple derivation of a simple GGA, in which all parameters (other than those in LSD) are fundamental constants. Only general features of the detailed construction underlying the Perdew-Wang 1991 (PW91) GGA are invoked. Improvements over PW91 include an accurate description of the linear response of the uniform electron gas, correct behavior under uniform scaling, and a smoother potential. [S0031-9007(96)01479-2] PACS numbers: 71.15.Mb, 71.45.Gm Kohn-Sham density functional theory [1,2] is widely used for self-consistent-field electronic structure calculations of the ground-state properties of atoms, molecules, and solids. In this theory, only the exchange-correlation energy EXC › EX 1 EC as a functional of the electron spin densities n"srd and n#srd must be approximated. The most popular functionals have a form appropriate for slowly varying densities: the local spin density (LSD) approximation Z d 3 rn e unif
146,533 citations
"First-Principles Investigation of P..." refers methods in this paper
...The generalized gradient approximation proposed by Perdew, Burke and Enzerhof (GGA-PBE) is adopted for exchange and correlation effects [17]....
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Book•
01 Jan 1954
TL;DR: Born and Huang's classic work on the dynamics of crystal lattices was published over thirty years ago, and it remains the definitive treatment of the subject as mentioned in this paper. But it is not the most complete work on crystal lattice dynamics.
Abstract: Although Born and Huang's classic work on the dynamics of crystal lattices was published over thirty years ago, the book remains the definitive treatment of the subject. It begins with a brief introduction to atomic forces, lattice vibrations and elasticity, and then breaks off into four sections. The first section deals with the general statistical mechanics of ideal lattices, leading to the electric polarizability and to the scattering of light. The second section deals with the properties of long lattice waves, the third with thermal properties, and the fourth with optical properties.
7,756 citations
"First-Principles Investigation of P..." refers background in this paper
...For cubic crystals, lattice stability requires the elastic stiffness constants that satisfy the following conditions [25]:...
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TL;DR: In this paper, the elastic and plastic properties of pure polycrystalline metals are discussed and a systematic relation between shear modulus, Burgers vector and plastic shear strength of metals possessing the same lattice structure is proposed.
Abstract: Relations between the elastic and plastic properties of pure polycrystalline metals are discussed and a systematic relation between shear modulus, Burgers vector and plastic shear strength of metals possessing the same lattice structure is proposed. In addition reasons are given for believing that in a limited temperature range malleability is related to Poisson's ratio.
5,719 citations
TL;DR: In this article, the tetrahedron method was used for Brillouin-zone integrations and a translational grid of k points and tetrahedral elements was proposed to obtain results for insulators identical to those obtained with special-point methods with the same number of points.
Abstract: Several improvements of the tetrahedron method for Brillouin-zone integrations are presented. (1) A translational grid of k points and tetrahedra is suggested that renders the results for insulators identical to those obtained with special-point methods with the same number of k points. (2) A simple correction formula goes beyond the linear approximation of matrix elements within the tetrahedra and also improves the results for metals significantly. For a required accuracy this reduces the number of k points by orders of magnitude. (3) Irreducible k points and tetrahedra are selected by a fully automated procedure, requiring as input only the space-group operations. (4) The integration is formulated as a weighted sum over irreducible k points with integration weights calculated using the tetrahedron method once for a given band structure. This allows an efficient use of the tetrahedron method also in plane-wave-based electronic-structure methods.
5,661 citations
"First-Principles Investigation of P..." refers methods in this paper
...The electronic density of state (eDOS) is obtained using a modified tetrahedron method [18]....
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TL;DR: In this paper, the use of quantum mechanics to make structural predictions and provide insights at the atomic level is reviewed with respect to intermetallics, and the question is addressed of why some tetragonal D022 trialuminides (e.g. TiAl3) can be stabilised with the cubic L12 structure by alloying additions but others cannot, and why if the cubic phase is stabilised, it remains brittle.
Abstract: Recent developments in the use of quantum mechanics to make structural predictions and provide insights at the atomic level are reviewed with respect to intermetallics. In particular, the question is addressed of why some tetragonal D022 trialuminides (e.g. TiAl3) can be stabilised with the cubic L12 structure by alloying additions but others (e.g. NbAl3) cannot, and why, if the cubic phase is stabilised, it remains brittle.MST/1543
1,299 citations
"First-Principles Investigation of P..." refers background in this paper
...On the other hand, Pettifor [27] proposed that the bonding character, reflecting the ductile/brittle behaviors of materials, could be described by the Cauchy pressure C12C44....
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...On the other hand, Pettifor [27] proposed that the bonding character, reflecting the ductile/brittle behaviors of materials, could be described by the Cauchy pressure C12C44....
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