scholarly journals First-Principles Calculation for the Influence of C and O on the Mechanical Properties of γ-TiAl Alloy at High Temperature

Metals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 262
Author(s):  
Jiahua Wang ◽  
Yong Lu ◽  
Xiaohong Shao
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
First Principles ◽  
Tial Alloy ◽  
Mechanical Performance ◽  
Phonon Dispersion ◽  
External Pressure ◽  
First Principles Calculation ◽  
Insight Into ◽  
Phonon Dispersion Relations

The elastic constants of temperature dependence, thermal expansion coefficient and phonon dispersion relations of γ-TiAl doped with C/O have been investigated using first-principles calculations in order to gain insight into the mechanical performance of γ-TiAl in cases of high temperature. This study shows that γ-TiAl maintains stability at high temperatures introduced by C or O atoms. Importantly, the hardness increases and retains excellent resistance to external pressure. The results indicate that even if the TiAl alloy is doped with C or O atoms, it can also exhibit excellent mechanical properties at a high temperature.

Effect of Alloying Elements V, Cr and Ni on the Electronic Structure and Mechanical Properties of FeAl from First-Principles Calculation

2014 ◽  
Vol 887-888 ◽  
pp. 378-383 ◽  
Author(s):  
Yu Chen ◽  
Zheng Jun Yao ◽  
Ping Ze Zhang ◽  
Dong Bo Wei ◽  
Xi Xi Luo ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Electronic Structure ◽  
Elastic Constants ◽  
First Principles ◽  
Density Functional ◽  
Valence Bond ◽  
Ternary Alloys ◽  
First Principles Calculation ◽  
Structure Stability ◽  
Alloying Element

The structure stability, mechanical properties and electronic structures of B2 phase FeAl intermetallic compounds and FeAl ternary alloys containing V, Cr or Ni were investigated using first-principles density functional theory calculations. Several models are established. The total energies, cohesive energies, lattice constants, elastic constants, density of states, and the charge densities of Fe8Al8 and Fe8XAl7 ( X=V, Cr, Ni ) are calculated. The stable crystal structures of alloy systems are determined due to the cohesive energy results. The calculated lattice contants of Fe-Al-X ( X= V, Cr, Ni) were found to be related to the atomic radii of the alloy elements. The calculation and analysis of the elastic constants showed that ductility of FeAl alloys was improved by the addition of V, Cr or Ni, the improvement was the highest when Cr was used. The order of the ductility was as follows: Fe8CrAl7 > Fe8NiAl7 > Fe8VAl7 > Fe8Al8. The results of electronic structure analysis showed that FeAl were brittle, mainly due to the orbital hybridization of the s, p and d state electron of Fe and the s and p state electrons of Al, showing typical characteristics of a valence bond. Micro-mechanism for improving ductility of FeAl is that d orbital electron of alloying element is maily involved in hybridization of FeAl, alloying element V, Cr and Ni decrease the directional property in bonding of FeAl.

First-principles calculation of mechanical properties of simulated debris ZrxU1−xO2

2019 ◽  
Vol 56 (9-10) ◽  
pp. 915-921 ◽  
Author(s):  
Mitsuhiro Itakura ◽  
Hiroki Nakamura ◽  
Toru Kitagaki ◽  
Takanori Hoshino ◽  
Masahiko Machida
Keyword(s):  
Mechanical Properties ◽  
First Principles ◽  
First Principles Calculation

Mechanical Properties and Size Effects of ZnO Nanowires Studied by First-Principles Calculation

2010 ◽  
Vol 654-656 ◽  
pp. 1670-1673
Author(s):  
Zhan Jun Gao ◽  
You Song Gu ◽  
Yue Zhang
Keyword(s):  
Mechanical Properties ◽  
First Principles ◽  
Size Effects ◽  
Density Functional ◽  
Elastic Moduli ◽  
Axial Direction ◽  
Zno Nanowires ◽  
First Principles Calculation ◽  
Different Diameters ◽  
Ground State Energies

First-principles density functional calculations were performed to investigate mechanical properties of ZnO nanowires and the size effects. Structural optimizations were performed first, and a series of strains were applied to the nanowires in the axial direction. The ground state energies were calculated and the elastic moduli of ZnO nanowires were obtained from the energy versus strain curves. It is found that the elastic moduli of the ZnO nanowires with three different diameters (1.2, 1.5 and 1.8nm) are 136.3, 138.7 and 138.0 GPa, respectively, and that of bulk ZnO along [0001] direction is 140.1 GPa. The elastic modulus of ZnO nanowire is slightly lower than that of the bulk and it decreases as the diameter decreases. Comparisons to experimental results and theoretical predications are made.

Pressure effects on mechanical and electronic properties of metallic C14 by first-principles calculation

2019 ◽  
Vol 33 (18) ◽  
pp. 1950193
Author(s):  
Yingjiao Zhou ◽  
Qun Wei ◽  
Bing Wei ◽  
Ruike Yang ◽  
Ke Cheng ◽  
...  
Keyword(s):  
High Pressure ◽  
Thermodynamic Properties ◽  
First Principles ◽  
Pressure Range ◽  
Phonon Dispersion ◽  
Elastic Anisotropy ◽  
Acoustic Velocity ◽  
Pressure Effects ◽  
First Principles Calculation ◽  
First Principles Calculations

The elastic constants and phonon dispersion of metallic C[Formula: see text] are calculated by first-principles calculations. The results show that the metallic C[Formula: see text] is mechanically and dynamically stable under high pressure. The variations of G/B ratio, Poisson’s ratio, elastic anisotropy, acoustic velocity and Debye temperature at the pressure range from 0 GPa to 100 GPa are analyzed. The results reveal that by adjusting the pressures the elastic anisotropy and thermodynamic properties could be improved for better applicability.

scholarly journals Insight into the Topological Nodal Line Metal YB2 with Large Linear Energy Range: A First-Principles Study

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3841
Author(s):  
Yang Li ◽  
Jihong Xia ◽  
Rabah Khenata ◽  
Minquan Kuang
Keyword(s):  
Energy Range ◽  
First Principles ◽  
Phonon Dispersion ◽  
Nodal Line ◽  
Spin Orbit Coupling ◽  
Metallic Material ◽  
Nodal Lines ◽  
Band Crossing ◽  
Crossing Point ◽  
Insight Into

The presence of one-dimensional (1D) nodal lines, which are formed by band crossing points along a line in the momentum space of materials, is accompanied by several interesting features. However, in order to facilitate experimental detection of the band crossing point signatures, the materials must possess a large linear energy range around the band crossing points. In this work, we focused on a topological metal, YB2, with phase stability and a P6/mmm space group, and studied the phonon dispersion, electronic structure, and topological nodal line signatures via first principles. The computed results show that YB2 is a metallic material with one pair of closed nodal lines in the kz = 0 plane. Importantly, around the band crossing points, a large linear energy range in excess of 2 eV was observed, which was rarely reported in previous reports that focus on linear-crossing materials. Furthermore, YB2 has the following advantages: (1) An absence of a virtual frequency for phonon dispersion, (2) an obvious nontrivial surface state around the band crossing point, and (3) small spin–orbit coupling-induced gaps for the band crossing points.

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