A comparison of the ideal strength between L12Co3(Al,W) and Ni3Al under tension and shear from first-principles calculations

2009 ◽  
Vol 94 (26) ◽  
pp. 261909 ◽  
Author(s):  
Yun-Jiang Wang ◽  
Chong-Yu Wang
Keyword(s):  
First Principles ◽  
First Principles Calculations ◽  
Ideal Strength ◽  
The Ideal

On the Possibility of Passivation of Si(100) by Adsorption of Group-VI Atoms

1990 ◽  
Vol 193 ◽  
Author(s):  
Efthimios Kaxiras
Keyword(s):  
First Principles ◽  
Relative Strength ◽  
Energy Costs ◽  
First Principles Calculations ◽  
Qualitative Information ◽  
Group Vi ◽  
Covalent Bonds ◽  
Large Dispersion ◽  
Monolayer Coverage ◽  
The Ideal

ABSTRACTThe possibility of passivating the Si(100) surface by adsorption of Group-VI atoms (S and Se) is investigated through first-principles calculations. The structure of the ideal (1×1) configuration with the Si surface dangling bonds saturated by full monolayer coverage is examined in detail. The Group-VI adsorbates form covalent bonds to the substrate with bond-lengths very close to the sums of the covalent radii. The bond-angles are larger than in bulk configurations of the Group-VI elements. The ideal (1×1) configuration gives rise to a surface electronic state with large dispersion spanning the entire band-gap of Si. Deviations from this configuration by in-phase or out-of-phase tilting of the adsorbate atoms result in energy costs which can give qualitative information on the relative strength of adsorbate-adsorbate and adsorbate-substrate interactions.

First-Principles Calculations of Grain Boundary-Surface for Various Grain Boundaries with Different Energies in Aluminum

2007 ◽  
Vol 551-552 ◽  
pp. 331-336 ◽  
Author(s):  
Tokuteru Uesugi ◽  
Y. Inoue ◽  
Yorinobu Takigawa ◽  
Kenji Higashi
Keyword(s):  
Shear Strength ◽  
Grain Boundary ◽  
First Principles ◽  
Boundary Surface ◽  
Grain Boundary Sliding ◽  
Excess Energy ◽  
First Principles Calculations ◽  
Perfect Single Crystal ◽  
Boundary Sliding ◽  
The Ideal

The grain boundary surface is the excess energy of the grain boundary as the lattice on one side of the grain is translated relative to the lattice on the other side of the grain. The maximum in the slope of the grain boundary surface determines the ideal shear strength for the grain boundary sliding. We presented the ideal shear strength for the grain boundary sliding in aluminum Σ3(11 2)[110] tilt grain boundary from the first-principles calculations. The ideal shear strength for the grain boundary sliding was much smaller than the ideal shear strength of a perfect single crystal.

The Clustering of Zn6Y9 and its Predominant Role in Long Period Stacking Order Phases in Mg-Zn-Y Alloys: A First-Principles Study

2013 ◽  
Vol 749 ◽  
pp. 569-576 ◽  
Author(s):  
Shang Yi Ma ◽  
Li Min Liu ◽  
Shao Qing Wang
Keyword(s):  
First Principles ◽  
Building Block ◽  
Stacking Fault ◽  
First Principles Calculations ◽  
Predominant Role ◽  
Lpso Phase ◽  
Local Structures ◽  
Long Period ◽  
Stacking Order ◽  
The Ideal

The local structures of Zn and Y in the long period stacking order (LPSO) phase in Mg-Zn-Y system were investigated by first principles calculations in details. The clustering of Zn and Y atoms ranging from single stacking fault layer to four consecutive layers was explicitly demonstrated. The calculations indicate that Zn and Y atoms prefer clustering in the form of Zn6Y9 embedding in ABCA-type building block to the random or ordered arrangements of Zn and Y atoms being enriched in two stacking fault layers. The cluster of Zn6Y9 can be regarded as the ideal stoichiometric component of LPSO and it plays a predominant role in the LPSO phases. The formation of LPSO phases is highly associated with the Zn6Y9 cluster and its derivatives.

scholarly journals Characterizing modulated structures with first-principles calculations: a unified superspace scheme of ordering in mullite

2019 ◽  
Vol 75 (2) ◽  
pp. 260-272 ◽  
Author(s):  
Paul Benjamin Klar ◽  
Iñigo Etxebarria ◽  
Gotzon Madariaga
Keyword(s):  
Phase Diagram ◽  
Density Functional Theory ◽  
First Principles ◽  
Density Functional ◽  
Complex Nature ◽  
First Principles Calculations ◽  
Functional Theory ◽  
Modulated Structures ◽  
Total Energies ◽  
The Ideal

The benefit of computational methods applying density functional theory for the description and understanding of modulated crystal structures is investigated. A method is presented which allows one to establish, improve and test superspace models including displacive and occupational modulation functions from first-principles calculations on commensurate structures. The total energies of different configurations allow one to distinguish stable and less stable structure models. The study is based on a series of geometrically optimized superstructures of mullite (Al4+2x Si2−2x O10−x ) derived from the superspace group Pbam(α0½)0ss. Despite the disordered and structurally complex nature of mullite, the calculations on ordered superstructures are very useful for determining the ideal Al/Si ordering in mullite, extracting atomic modulation functions as well as understanding the SiO2–Al2O3 phase diagram. The results are compared with experimentally established models which confirm the validity and utility of the presented method.

scholarly journals Ultimate Mechanical Properties of Forsterite

Minerals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 787 ◽  
Author(s):  
Karine Gouriet ◽  
Philippe Carrez ◽  
Patrick Cordier
Keyword(s):  
Mechanical Properties ◽  
First Principles ◽  
Shear Plane ◽  
Shear Loading ◽  
High Symmetry ◽  
First Principles Calculations ◽  
Generalized Gradient ◽  
Generalized Gradient Approximation ◽  
Homogeneous Strain ◽  
The Ideal

The ultimate mechanical properties, as characterized here by the ideal strengths of Mg2SiO4 forsterite, have been calculated using first-principles calculations and generalized gradient approximation under tensile and shear loading. The ideal tensile strengths (ITS) and ideal shear strengths (ISS) are computed by applying homogeneous strain increments along high-symmetry directions ([100], [010], and [001]) and low index shear plane ((100), (010), and (001)) of the orthorhombic lattice. We show that the ultimate mechanical properties of forsterite are highly anisotropic, with ITS ranging from 12.1 GPa along [010] to 29.3 GPa along [100], and ISS ranging from 5.6 GPa for simple shear deformation along (100) to 11.5 GPa for shear along (010).

Effect of alloying elements on the ideal strength and charge redistribution of γ′-Ni3Al: a first-principles study of tensile deformation

RSC Advances ◽  
2016 ◽  
Vol 6 (81) ◽  
pp. 77489-77498 ◽  
Author(s):  
Minru Wen ◽  
Chong-Yu Wang
Keyword(s):  
Dft Calculations ◽  
First Principles ◽  
Tensile Deformation ◽  
Alloying Elements ◽  
Ideal Strength ◽  
Charge Redistribution ◽  
First Principles Study ◽  
The Ideal ◽  
Effect Of Alloying

The effect of the alloying elements on the σIT of γ′-Ni3Al along three characteristic directions was investigated using DFT calculations.

Mechanical Properties and Stability of Body-Centered-Tetragonal C8 at High Pressures

2018 ◽  
Vol 73 (10) ◽  
pp. 939-945
Author(s):  
Chenyang Zhao ◽  
Qun Wei ◽  
Haiyan Yan ◽  
Bing Wei
Keyword(s):  
Mechanical Properties ◽  
First Principles ◽  
Pressure Range ◽  
Superhard Material ◽  
High Pressures ◽  
Elastic Anisotropy ◽  
Acoustic Velocity ◽  
Large Strains ◽  
First Principles Calculations ◽  
The Ideal

AbstractThe structural, mechanical, electronic properties and stability of body-centered-tetragonal C8 (Bct-C8) were determined by using the first-principles calculations. Bct-C8 is identified to be mechanically and dynamically stable at a pressure range from 0 to 100 GPa. The elastic anisotropy, average acoustic velocity and Debye temperature of Bct-C8 at ambient and high pressures were studied. The ideal stresses at large strains of Bct-C8 were examined; the results showed that it would cleave under the tensile strength of 72 GPa or under the shear strength of 70 GPa, indicating that Bct-C8 is a potential superhard material.

First Principles Study on Ideal Strength of Cu Multi-Shell Nano-Wire

2007 ◽  
Vol 345-346 ◽  
pp. 919-924
Author(s):  
Takayuki Kitamura ◽  
Akihiro Kushima ◽  
Yoshitaka Umeno
Keyword(s):  
First Principles ◽  
Maximum Stress ◽  
Atomic Chain ◽  
Ideal Strength ◽  
Young’S Moduli ◽  
Single Sheet ◽  
The Wire ◽  
Nano Wires ◽  
Insight Into ◽  
The Ideal

The ideal strength of a nano-component, which is the maximum stress of the structure, provides an insight into the mechanical behavior of minute material. We conducted tensile simulations for cylindrical-shaped Cu nano-wires composed of an atomic chain as a core wrapped around by shell(s) with the structure of (111) layers in an fcc crystal. The results are compared with Cu atomic chain and sheet which are components of the nanowire. Young’s moduli and the ideal strengths of the wires are less than a single atomic chain and a sheet. The mechanical strength of the wire is weakened by the following three factors: (A) Change in electron arrangement caused by combining core and shell; (B) Larger interatomic distance (inherent tensile strain) of the outer shell introduced by the mismatch of atomic layers due to the curvature difference; (C) Mismatch between shells due to curvature difference. Factor (A) reduces the bonding strength in the shell(s) that occupy a greater part of the wire. 5-1 wire, which consists of a core and a shell, is weaker than the single atomic chain and the single sheet due to (A) and (B). 10-5-1 wire, consisting of a core and two shells, has less strength than 5-1 wire due to (C) in addition to (A) and (B).

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