scholarly journals Анализ водородоустойчивости алюминиевых сплавов

2021 ◽  
Vol 47 (4) ◽  
pp. 15
Author(s):  
Д.А. Индейцев ◽  
Е.В. Осипова
Keyword(s):  
Mechanical Properties ◽  
Density Functional ◽  
Physical And Mechanical Properties ◽  
Covalent Radius ◽  
Chemical Bonds ◽  
Aluminum Compound ◽  
Functional Theory ◽  
Slowing Down ◽  
Stable Chemical ◽  
Hydrogen Resistance

It was established by the methods of quantum chemistry that tungsten W and rhenium Re are the most effective additives that increase the hydrogen resistance of aluminum Al. It is shown that W and Re strongly compress aluminum, but at the same time have a rather large covalent radius. In addition, each W and Re atom form stable chemical bonds with 12 Al atoms. As a result, the W and Re atoms strongly bind Al atoms significantly increasing the energy of vacancy formation and slowing down the process of hydrogen embrittlement. All basic physical and mechanical properties of the most hydrogen-resistant aluminum compound WReAl24 have been calculated using density functional theory.

scholarly journals First-Principles Study of the Stabilization and Mechanical Properties of Rare-Earth Ferritic Perovskites (RFeO3, R = La, Eu, Gd)

2020 ◽  
Vol 10 (11) ◽  
pp. 4008
Author(s):  
Mahdi Faghihnasiri ◽  
Vahid Najafi ◽  
Farzaneh Shayeganfar ◽  
Ali Ramazani
Keyword(s):  
Mechanical Properties ◽  
Rare Earth ◽  
First Principles ◽  
Density Functional ◽  
Mechanical Response ◽  
External Loading ◽  
Chemical Bonds ◽  
Functional Theory ◽  
Density Values ◽  
The Stability

Current research aims to investigate the mechanical properties of rare earth perovskite ferrites (RFeO3, R = La, Eu, Gd) utilizing density functional theory (DFT) calculations. Using the revised Perdew–Burke–Ernzerhof approximation for solids (PBEsol) approximation, the elastic constants, bulk, Young’s, and shear modulus, Poisson’s ratio, and anisotropic properties are calculated. The quantum theory of atoms in molecules (QTAIM) is employed to analyze the stability of chemical bonds in the structures subjected to an external loading. Based on these calculations, Fe-O and R-O bonds can be considered as nearly ionic, which is due to the large difference in electronegativity of R and Fe with O. Additionally, our results reveal that the charge density values of the Fe-O bonds in both structures remain largely outside of the ionic range. Finally, the mechanical response of LaFeO3, EuFeO3, and GdFeO3 compounds to various cubic strains is investigated. The results show that in RFeO3 by increasing the radius of the lanthanide atom, the mechanical properties of the material including Young’s and bulk modulus increase.

Ab Initio Calculation of Mechanical Properties of Stacking Fault in 3C-SiC: Effect of Stress and Doping

2012 ◽  
Vol 717-720 ◽  
pp. 415-418
Author(s):  
Yoshitaka Umeno ◽  
Kuniaki Yagi ◽  
Hiroyuki Nagasawa
Keyword(s):  
Mechanical Properties ◽  
Ab Initio ◽  
Density Functional ◽  
Stacking Faults ◽  
Single Layer ◽  
Local Strain ◽  
Density Functional Theory Calculations ◽  
Stacking Fault ◽  
Functional Theory ◽  
N Doping

We carry out ab initio density functional theory calculations to investigate the fundamental mechanical properties of stacking faults in 3C-SiC, including the effect of stress and doping atoms (substitution of C by N or Si). Stress induced by stacking fault (SF) formation is quantitatively evaluated. Extrinsic SFs containing double and triple SiC layers are found to be slightly more stable than the single-layer extrinsic SF, supporting experimental observation. Effect of tensile or compressive stress on SF energies is found to be marginal. Neglecting the effect of local strain induced by doping, N doping around an SF obviously increase the SF formation energy, while SFs seem to be easily formed in Si-rich SiC.

scholarly journals ADSORPTION OF NANOWOLLASTONITE ON CELLULOSE SURFACE: EFFECTS ON PHYSICAL AND MECHANICAL PROPERTIES OF MEDIUM-DENSITY FIBERBOARD (MDF)

CERNE ◽  
2016 ◽  
Vol 22 (2) ◽  
pp. 215-222 ◽  
Author(s):  
Hamid Reza Taghiyari ◽  
Roya Majidi ◽  
Asghar Jahangiri
Keyword(s):  
Mechanical Properties ◽  
Density Functional ◽  
Medium Density Fiberboard ◽  
Physical And Mechanical Properties ◽  
Mechanical Tests ◽  
National Standard ◽  
Medium Density ◽  
Wood Fibers ◽  
Strong Adsorption ◽  
Cellulose Surface

ABSTRACT Effects of nanowollastonite (NW) adsorption on cellulose surface were studied on physical and mechanical properties of medium-density fiberboard (MDF) panels; properties were then compared with those of MDF panels without NW-content. The size range of NW was 30-110 nm. The interaction between NW and cellulose was investigated using density functional theory (DFT). Physical and mechanical tests were carried out in accordance with the Iranian National Standard ISIRI 9044 PB Type P2 (compatible with ASTM D1037-99) specifications. Results of DFT simulations showed strong adsorption of NW on cellulose surface. Moreover, mechanical properties demonstrated significant improvement. The improvement was attributed to the strong adsorption of NW on cellulose surface predicted by DFT, adding to the strength and integrity between wood fibers in NW-MDF panels. It was concluded that NW would improve mechanical properties in MDF panels as a wood-composite material, as well as being effective in improving its biological and thermal conductivity.

First-principles study of phase stability, electronic and mechanical properties of plutonium sub-oxides

2019 ◽  
Vol 21 (30) ◽  
pp. 16818-16829 ◽  
Author(s):  
P. S. Ghosh ◽  
A. Arya
Keyword(s):  
Mechanical Properties ◽  
Density Functional Theory ◽  
Phase Stability ◽  
First Principles ◽  
Density Functional ◽  
Functional Theory ◽  
First Principles Study ◽  
Hubbard Parameter ◽  
Formation Energies

Formation energies of PuO2, α-Pu2O3 and sub-oxides PuO2−x (0.0 < x < 0.5) are determined using density functional theory employing generalised gradient approximation corrected with an effective Hubbard parameter.

Calculation of electronic structure and mechanical properties of DO3–Fe75-xSi25Nix intermetallic compounds by first principles

2015 ◽  
Vol 29 (13) ◽  
pp. 1550087
Author(s):  
R. Ma ◽  
M. P. Wan ◽  
J. Huang ◽  
Q. Xie
Keyword(s):  
Mechanical Properties ◽  
Intermetallic Compounds ◽  
First Principles ◽  
Electronic Structures ◽  
Density Functional ◽  
Elastic Parameters ◽  
Functional Theory ◽  
Ni Content ◽  
The Density Functional Theory ◽  
The Difference

Based on the density functional theory (DFT), the plane-wave pseudopotential method was used to investigate the electronic structures and mechanical properties of DO 3– Fe 75-x Si 25 Ni x(x = 0, 3.125, 6.25 and 9.375) intermetallic compounds. The elastic parameters were calculated, and then the bulk modulus, shear modulus and elastic modulus were derived. The paper then focuses on the discussion of ductility and plasticity. The results show that by adding appropriate Ni to Fe 3 Si intermetallic compound can improve the ductility. But the hardness will increase when the Ni content exceeds 6.25%. Analysis of density of states (DOS) and overlap populations indicates that with the difference of the strength of bonding and activity, there were some differences of ductility among different Ni contents. The Fe 71.875 Ni 3.125 Si 25 has the lowest hardness because the covalent bonding (Fe–Si bond and Si–Ni bond) has the minimum covalent electrons.

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