Vacancy-induced elastic properties and hardness of CrB4: A DFT calculation

2017 ◽  
Vol 31 (13) ◽  
pp. 1750096 ◽  
Author(s):  
Yong Pan ◽  
Song Chen ◽  
Yuanhua Lin
Keyword(s):  
Mechanical Properties ◽  
Dft Calculation ◽  
Covalent Bond ◽  
Elastic Stiffness ◽  
First Principle ◽  
Triangular Pyramid ◽  
First Principle Calculations ◽  
3D Network ◽  
Metal Borides ◽  
The Relationship

Vacancy plays a crucial role in mechanical properties of transition metal borides (TMBs). However, the influence of vacancy on hardness of TMBs is unknown. In this paper, the relationship between boron vacancy and mechanical properties of CrB4 is investigated by first-principle calculations. Two different vacancies including boron monovacancy (MV) and boron bivacancy (BV) are considered. We find that CrB4 with boron MV is more stable than that of boron BV. The removed atom weakens the deformation resistances, and reduces the elastic stiffness and hardness. The calculated shear modulus, Young’s modulus and theoretical hardness of boron MV are larger than that of boron BV. The reason is that the removed atom weakens the localized hybridization between B and B atoms, and damages the 3D-network B–B covalent bond. However, the bulk modulus of B[Formula: see text] is slightly larger than that of perfect CrB4. This reason is attributed to the formation of triangular pyramid bonding in B[Formula: see text] vacancy.

scholarly journals Effect of Nb on the Microstructure and Mechanical Properties of Ti2Cu Intermetallic through the First-Principle Calculations and Experimental Investigation

Metals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 547 ◽  
Author(s):  
Jialin Cheng ◽  
Yeling Yun ◽  
Jingjing Wang ◽  
Jiaxin Rui ◽  
Shun Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Experimental Investigation ◽  
Density Functional ◽  
Covalent Bond ◽  
First Principle ◽  
Compression Tests ◽  
Solid Solution Strengthening ◽  
First Principle Calculations ◽  
Fine Grain ◽  
Fine Grain Strengthening

Through the first-principle calculations based on density functional theory and experimental investigation, the structural stability elastic properties and mechanical properties of Ti2Cu and Ti18Cu5Nb1 intermetallics were studied. The first-principle calculations showed that the ratio of bulk modulus to shear modulus (B/G) and Poisson’s ratio (ν) of Ti2Cu and Ti18Cu5Nb1 intermetallics were 2.03, 0.288, and 2.22, 0.304, respectively, indicating that the two intermetallics were ductile. This was confirmed by the compression tests, which showed that the plastic strain of both intermetallics was beyond 25%. In addition, the yield strength increased from the 416 to 710 MPa with the addition of Nb. The increase in strength is the result of three factors, namely covalent bond tendency, fine grain strengthening, and solid solution strengthening. This finding gives clues to design novel intermetallics with excellent mechanical properties by first-principle calculations and alloying.

First-principle calculations of ternary compounds: Immm-BxTi3−xN2

2019 ◽  
Vol 33 (25) ◽  
pp. 1950295
Author(s):  
Xin-Kuan Wang ◽  
Ruike Yang ◽  
Shaowei Ma ◽  
Bao Chai ◽  
Minhua Xue
Keyword(s):  
Optical Properties ◽  
Plasma Frequency ◽  
Titanium Nitrides ◽  
First Principle ◽  
Orthorhombic Structure ◽  
Cutting Resistance ◽  
Ternary Compounds ◽  
First Principle Calculations ◽  
The Relationship ◽  
Boron Nitrogen

Boron nitride (BN) and Titanium nitrides (TiNs) have been successfully researched recently. In order to analyze the relationship among the Boron, Nitrogen and Titanium, the ternary compounds with an orthorhombic structure Immm- are studied. We further researched on the mechanical, electronic and optical properties of new Immm-B[Formula: see text]Ti[Formula: see text]N2 ([Formula: see text]). The structures of BTi2N2 and B2TiN2 are mechanically stable at 0, 50 and 100 GPa. The BTi2N2 has the higher cutting resistance and better ductility than the B2TiN2. The higher Young’s modulus of B2TiN2 indicates the B2TiN2 is stiffer than BTi2N2. The BTi2N2 is harder to compress in the [Formula: see text] direction and the B2TiN2 is harder in [Formula: see text] direction. Immm-BTi2N2 and B2TiN2 have good metallicity at 0 and 100 GPa. Immm-BTi2N2 has the higher dielectric function than B2TiN2 and the plasma frequency of B2TiN2 is bigger than that of BTi2N2. We hope our work will provide some help to the experimental work about the technology of the material.

Mechanical properties of layered oxysulfide CaZnOS from first principle calculations

2016 ◽  
Vol 670 ◽  
pp. 41-47 ◽  
Author(s):  
Zhi-Jun Zhang ◽  
Ang Feng ◽  
Shao-Lin Zhang ◽  
Wei-Bin Zhang ◽  
Woochul Yang
Keyword(s):  
Mechanical Properties ◽  
First Principle ◽  
First Principle Calculations

Chemical bonding and mechanical properties of M2AC (M = Ti, V, Cr, A = Al, Si, P, S) ceramics from first-principles investigations

2009 ◽  
Vol 24 (2) ◽  
pp. 556-564 ◽  
Author(s):  
Ting Liao ◽  
Jingyang Wang ◽  
Yanchun Zhou
Keyword(s):  
Mechanical Properties ◽  
Chemical Bonding ◽  
First Principles ◽  
General Trend ◽  
Elastic Stiffness ◽  
Group Element ◽  
Max Phase ◽  
Early Transition Metal ◽  
The Relationship ◽  
Bonding Characteristic

MAX-phase carbides (M is an early transition metal, A is an A-group element) exhibit an interesting bonding characteristic of alternative stacking of strong M–C bonds and relatively weak M–A bonds in one direction. In the present first-principles total energy calculations, we establish the relationship between mechanical properties and electronic structure for ternary M2AC (M = Ti, V, Cr, A = Al, Si, P, S) carbides. By systematically tuning elements on the M and A sites, pronounced enhancements of bulk modulus, elastic stiffness, and ideal shear strength are achieved in V-containing V2AC (A = Al, Si, P, and S) carbides. It is suggested that tailoring on the A site is more efficient than on the M site in strengthening the mechanical properties of studied serial carbides. The results highlight a general trend for tailor-made mechanical properties of ternary M2AC carbides by control of chemical bonding.

Covalent Bond Cluster Effects and Phase Transitions in Superconductor Mg1-xAlxB2 Compounds

2011 ◽  
Vol 55-57 ◽  
pp. 950-954
Author(s):  
Yan Bao ◽  
Yuan Zhao ◽  
Ni Zhu
Keyword(s):  
Phase Transitions ◽  
Band Structure ◽  
Covalent Bond ◽  
Doping Effect ◽  
Experimental Measurements ◽  
First Principle ◽  
Density Of State ◽  
First Principle Calculations ◽  
Densities Of States ◽  
Theoretical Predictions

First-principle calculations were performed for the study of the superconductor MgB2and AlB2. The doping effect of compound Mg1-xAlxB2was analyzed by supercell method. Band structure, electronic bands structure, total and partial densities of states were calculated and analyzed in detail. Covalent bond effects (CBC) appeared in the electronic bands structure when doping Al to MgB2. It is found that this CBC effects on Mg1-xAlxB2samples have prominent relations to superconductivity. The study of the density of state indicates that the superconductivity decreases with the increase of compound Al. In particular, there exists the transition of superconductor to non-superconductor with the change of x. The theoretical predictions agreed well with experimental measurements.

The dataset of covalent bond lengths resulting from the first-principle calculations

2019 ◽  
Vol 1163 ◽  
pp. 112508 ◽  
Author(s):  
Tymofii Yu. Nikolaienko ◽  
Valerii S. Chuiko ◽  
Leonid A. Bulavin
Keyword(s):  
Covalent Bond ◽  
First Principle ◽  
Bond Lengths ◽  
First Principle Calculations
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