Response of fcc metals andL12andD022type trialuminides to uniaxial loading along [100] and [001]:ab initioDFT calculations

Jahnátek, Michal; Krajčı́, M.; Hafner, J.

doi:10.1080/14786435.2010.523720

Cited by 11 publications

(3 citation statements)

References 42 publications

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“…The shear deformations have been performed in an alias mode; 29,30,48 that is, the strain is applied to the top layer of the supercell, while the bottom layer is kept in a fixed position and all intermediate layers are free to relax. The alias regime provides a more realistic description of a shear deformation than an affine transformation applied to all coordinates in the cell.…”

Section: A {211} 111 Shear Deformationmentioning

confidence: 99%

“…Again the energy-strain and stress-strain curves of NiAl and FeAl were found to be very different, leading to the conclusion that the instabilities under 111 shearing and 100 tension can be attributed to the same mechanism for FeAl, but not for NiAl. Jahnatek et al 29,30 have demonstrated that the chemical decoration of the fcc lattice in L1 2 and D0 22 -type trialuminides of Sc, Ti, and V determines similarities and differences in the response to 110 and 100 uniaxial loading compared to fcc Al.…”

Section: Introductionmentioning

confidence: 99%

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Ideal tensile and shear strength of a gum metal approximant:Ab initiodensity functional calculations

2012

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The ideal tensile and shear strengths of binary β-phase Ti 3 Nb alloys have been investigated using ab initio density functional calculations. The binary alloy is considered as an approximant to the multifunctional Ti-Nb-Ta-Zr-O alloy known as "gum metal," which displays high strength, low elastic modulus, high yield strain, and very good ductility. This alloy has been reported to deform elastically until the stress approaches the ideal tensile strength. Our calculations have been performed for an optimized chemical decoration of the body-centered cubic (bcc) structure of the β phase. Previous work has demonstrated that this model yields elastic constants in very good agreement with those measured for gum metal specimens and leads to a reasonably accurate description of the martensitic transformations between the bcc β, the orthorhombic α and the hexagonal ω phases [Lazar et al., Phys. Rev. B 84, 054202 (2011)]. The simulations of the response to tensile and shear loading have been performed for large supercells which account also for the different orientations of the-Nb-Nb-chains characteristic for the β-phase structure relative to the direction of the applied load. The energy-strain and stress-strain curves are found to be very different from those reported for all bcc metals. Under uniaxial 100 loading we find an ideal tensile strength of 2.4 GPa, the upper limit to the tensile stress arising from a shear instability of the structure. Under uniaxial 110 load we calculate an ideal tensile strength of 2.2 or 2.8 GPa, depending on the orientation of the-Nb-Nb-chains relative to the loading direction. For a realistic multidomain structure the ideal strength is expected to correspond to the average of these values. An ideal strength of 2.6 GPa under 110 loading is roughly the same as under 100 load, despite a considerable anisotropy of the tensile moduli. For {211} 111 shear we calculate an ideal shear strength of 1.6 GPa, again as an average over different possible shearing directions relative to the Nb-Nb bonds. For the {110} 110 shear system we find a lower strength of 0.9 GPa. The structures reached at the stress maximum under 100 uniaxial tension and {211} 111 shear are identical, and since the maximal shear stress is much lower than the tensile stress, the alloy will fail by shear even under strictly uniaxial tension. The values of the ideal tensile and shear strengths are significantly low, even in comparison with those calculated for bcc V and Nb with very small shear moduli and approach the values reported for gum metal alloys.

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Section: A {211} 111 Shear Deformationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Ideal tensile and shear strength of a gum metal approximant:Ab initiodensity functional calculations

2012

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“…However, it is generally believed that the lower symmetry of D0 22 structure is the main cause of poor ductility. Many attempts had been made to convert D0 22 into L1 2 , which can make the aluminide have good ductility [12][13][14][15]. However, the D0 22 structure has a good strengthening effect in the recent design of high entropy alloy.…”

Section: Introductionmentioning

confidence: 99%

Exploration of D022-Type Al3TM(TM = Sc, Ti, V, Zr, Nb, Hf, Ta): Elastic Anisotropy, Electronic Structures, Work Function and Experimental Design

Zhang

Sun

et al. 2021

Materials

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The structural properties, elastic anisotropy, electronic structures and work function of D022-type Al3TM (TM = Sc, Ti, V, Y, Zr, Nb, La, Hf, Ta) are studied using the first-principles calculations. The results indicate that the obtained formation enthalpy and cohesive energy of these compounds are in accordance with the other calculated values. It is found that the Al3Zr is the most thermodynamic stable compound. The mechanical property indexes, such as elastic constants, bulk modulus, shear modulus, Young’s modulus, Poisson’s ratio, and Vickers hardness are systematically explored. Moreover, the calculated universal anisotropic index, percent anisotropy and shear anisotropic factors of D022-type Al3TM are analyzed carefully. It demonstrates that the shear modulus anisotropy of Al3La is the strongest, while that of Al3Ta is the weakest. In particular, the density of states at Fermi level is not zero, suggesting that these phases have metal properties and electrical conductivity. More importantly, the mechanisms of correlation between hardness and Young’s modulus are further explained by the work function. Finally, the experimental design proves that D022-Al3Ta has an excellent strengthening effect.

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Mechanical Properties Evaluation of Zr Addition in L12-Al3(Sc1−x Zr x ) Using First-Principles Calculation

Qian

Xue

Wang

et al. 2016

JOM

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Response of fcc metals andL1₂andD0₂₂type trialuminides to uniaxial loading along [100] and [001]:ab initioDFT calculations

Cited by 11 publications

References 42 publications

Ideal tensile and shear strength of a gum metal approximant:Ab initiodensity functional calculations

Ideal tensile and shear strength of a gum metal approximant:Ab initiodensity functional calculations

Exploration of D022-Type Al3TM(TM = Sc, Ti, V, Zr, Nb, Hf, Ta): Elastic Anisotropy, Electronic Structures, Work Function and Experimental Design

Mechanical Properties Evaluation of Zr Addition in L12-Al3(Sc1−x Zr x ) Using First-Principles Calculation

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