scholarly journals Elastic Parameters of Paramagnetic Fe–20Cr–20Ni-Based Alloys: A First-Principles Study

Metals ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 792 ◽  
Author(s):  
Noura Al-Zoubi
Keyword(s):  
First Principles ◽  
Theoretical Data ◽  
Austenitic Stainless Steels ◽  
Energy Difference ◽  
Local Magnetic Moment ◽  
Face Centered Cubic ◽  
Elastic Parameters ◽  
Starting Point ◽  
Fcc Phase ◽  
Random Alloys

The single-crystal and polycrystalline elastic parameters of paramagnetic Fe0.6−xCr0.2Ni0.2Mx (M = Al, Co, Cu, Mo, Nb, Ti, V, and W; 0 ≤ x ≤ 0.08) alloys in the face-centered cubic (fcc) phase were derived by first-principles electronic structure calculations using the exact muffin-tin orbitals method. The disordered local magnetic moment approach was used to model the paramagnetic phase. The theoretical elastic parameters of the present Fe–Cr–Ni-based random alloys agree with the available experimental data. In general, we found that all alloying elements have a significant effect on the elastic properties of Fe–Cr–Ni alloy, and the most significant effect was found for Co. A correlation between the tetragonal shear elastic constant C′ and the structural energy difference ΔE between fcc and bcc lattices was demonstrated. For all alloys, small changes in the Poisson’s ratio were obtained. We investigated the brittle/ductile transitions formulated by the Pugh ratio. We demonstrate that Al, Cu, Mo, Nb, Ti, V, and W dopants enhance the ductility of the Fe–Cr–Ni system, while Co reduces it. The present theoretical data can be used as a starting point for modeling the mechanical properties of austenitic stainless steels at low temperatures.

ELASTIC CONSTANTS OF d TRANSITION ELEMENTS AND d TRANSITION ALLOYS

1993 ◽  
Vol 07 (01n03) ◽  
pp. 203-206 ◽  
Author(s):  
PER SÖDERLIND ◽  
JOHN WILLS ◽  
OLLE ERIKSSON
Keyword(s):  
Crystal Structure ◽  
Elastic Constant ◽  
Elastic Constants ◽  
First Principles ◽  
Theoretical Data ◽  
Energy Difference ◽  
Transition Elements ◽  
Virtual Crystal Approximation ◽  
Theoretical Results ◽  
Theory And Experiment

The shear elastic constant, C′, is calculated from first principles for the cubic 4d and 5d transition elements. This study also includes calculations for selected alloys using the virtual crystal approximation. The tetragonal shear constant for these elements and alloys is found to follow a trend which can be related to the calculated crystal structure stabilities. In fact, the trend of C′ behaves roughly as the the trend displayed by the energy difference between the fcc and bcc crystal structures. The theoretical results are generally in ~90% agreement with experiment for the tetragonal shear constant and this implies indirectly that the discrepancy between theory and experiment found for the crystal energies do not lie in the theoretical data.

Theoretical Investigation of Carbon Atom Adsorption and Diffusion on the Surfaces of Cu

2014 ◽  
Vol 1082 ◽  
pp. 475-479
Author(s):  
Liang Qiao ◽  
Shu Jie Liu ◽  
Xiao Ying Hu ◽  
Li Li Wang ◽  
Dong Mei Bi
Keyword(s):  
Carbon Atom ◽  
First Principles ◽  
Density Functional ◽  
Energy Difference ◽  
Face Centered Cubic ◽  
Functional Theory ◽  
Hexagonal Close Packed ◽  
Adsorbed Carbon ◽  
Face Centered ◽  
And Diffusion

The adsorption and diffusion of carbon atom on Cu (111) and (100) surfaces have been investigated based on first-principles density-functional theory. For Cu (111) surface, the hexagonal close-packed and face-centered cubic sites are the most stable sites with little energy difference in the adsorption energy. For Cu (100) surface, the hollow site is the most stable. There is charge transfer from Cu surface to the adsorbed carbon atom. Moreover, the diffusions of carbon atom on Cu surfaces have been investigated, and the results show that the diffusion of carbon atom prefers to happen on Cu (111) surface.

Interface Structure of Some Precipitates in Austenitic Stainless Steels

1981 ◽  
Vol 39 ◽  
pp. 292-293
Author(s):  
J. Bentley
Keyword(s):  
Dominant Role ◽  
Austenitic Stainless Steels ◽  
Lattice Parameter ◽  
Interfacial Structure ◽  
Detailed Knowledge ◽  
Face Centered Cubic ◽  
Orientation Relationships ◽  
The Matrix ◽  
High Resolution Tem ◽  
Fcc Phase

Interphase boundaries often play a dominant role in high-temperature materials properties such as deformation and fracture or radiation damage. A detailed knowledge of the interfacial structure is required to understand the relationship between microstructure and properties. High-resolution TEM observations have been made of the interfacial structure of two carbides (M23C6 and MC) and an intermetallic compound (sigma) in 300 series austenitic stainless steels.Precipitates with well-defined orientation relationships and interface planes were chosen in order that the determined structures would be generally applicable in a range of property-structure correlations.Chromium-rich M23C6 (τ) is a face-centered cubic (fcc) phase with a lattice parameter (ao)τ ∼ 1.06 nm ≈ 2.97(ao)γ which forms with a cube-on-cube orientation relationship with the matrix (γ) and with {111} and {110} interfaces. In order to accommodate the “mismatch” of ∼1% between the matrix and precipitate, interface dislocations with separations of 10—20 nm are expected and have been observed previously.

scholarly journals Effect of Ti Content on the Microstructure and Corrosion Resistance of CoCrFeNiTix High Entropy Alloys Prepared by Laser Cladding

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2209 ◽  
Author(s):  
Xinyang Wang ◽  
Qian Liu ◽  
Yanbin Huang ◽  
Lu Xie ◽  
Quan Xu ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Laser Cladding ◽  
First Principles ◽  
High Entropy Alloy ◽  
Face Centered Cubic ◽  
First Principles Calculations ◽  
High Entropy ◽  
Niti Phase ◽  
Fcc Phase ◽  
Ti Content

In this paper, CoCrFeNiTix high entropy alloy (HEA) coatings were prepared on the surface of Q235 steel by laser cladding. The microstructure, microhardness, and corrosion resistance of the coatings were studied. The mechanism of their corrosion resistance was elucidated experimentally and by first-principles calculations. The results show that CoCrFeNiTi0.1 adopts a face-centered cubic (FCC) phase, CoCrFeNiTi0.3 exhibits an FCC phase and a tetragonal FeCr phase, and CoCrFeNiTi0.5 adopts an FCC phase, a tetragonal FeCr phase, and a rhombohedral NiTi phase. The FCC phase, tetragonal FeCr phase, rhombohedral NiTi phase, and hexagonal CoTi phase are all observed in the CoCrFeNiTi0.7 HEA. The alloys assume the dendritic structure that is typical of HEAs. Ni and Ti are enriched in the interdendritic regions, whereas Cr and Fe are enriched in the dendrites. With increasing Ti content, the hardness of the cladding layers also increases due to the combined effects of lattice distortion and dispersion strengthening. When exposed to a 3.5 wt.% NaCl solution, pitting corrosion is the main form of corrosion on the CoCrFeNiTix HEA surfaces. The corrosion current densities of CoCrFeNiTix HEAs are much lower than those of other HEAs. As the Ti content increases, the corrosion resistance is improved. Through X-ray photoelectron spectroscopy (XPS) and first-principles calculations, the origin of the higher corrosion resistance of the coatings is connected to the presence of a dense passivation film. In summary, the corrosion resistance and mechanical properties of CoCrFeNiTi0.5 alloy are much better than the other three groups, which promotes the development of HEA systems with high value for industrial application.

scholarly journals Stability and equation of state of face-centered cubic and hexagonal close packed phases of argon under pressure

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Agnès Dewaele ◽  
Angelika D. Rosa ◽  
Nicolas Guignot ◽  
Denis Andrault ◽  
João Elias F. S. Rodrigues ◽  
...  
Keyword(s):  
Equation Of State ◽  
Single Crystal ◽  
Single Crystal Sample ◽  
Moderate Pressure ◽  
Face Centered Cubic ◽  
Experimental Conditions ◽  
Crystal Sample ◽  
Hexagonal Close Packed ◽  
Face Centered ◽  
Fcc Phase

AbstractThe compression of argon is measured between 10 K and 296 K up to 20 GPa and and up to 114 GPa at 296 K in diamond anvil cells. Three samples conditioning are used: (1) single crystal sample directly compressed between the anvils, (2) powder sample directly compressed between the anvils, (3) single crystal sample compressed in a pressure medium. A partial transformation of the face-centered cubic (fcc) phase to a hexagonal close-packed (hcp) structure is observed above 4.2–13 GPa. Hcp phase forms through stacking faults in fcc-Ar and its amount depends on pressurizing conditions and starting fcc-Ar microstructure. The quasi-hydrostatic equation of state of the fcc phase is well described by a quasi-harmonic Mie–Grüneisen–Debye formalism, with the following 0 K parameters for Rydberg-Vinet equation: $$V_0$$ V 0 = 38.0 Å$$^3$$ 3 /at, $$K_0$$ K 0 = 2.65 GPa, $$K'_0$$ K 0 ′ = 7.423. Under the current experimental conditions, non-hydrostaticity affects measured P–V points mostly at moderate pressure ($$\le$$ ≤ 20 GPa).

Elastic anharmonicity of bcc Fe and Fe-based random alloys from first-principles calculations

2017 ◽  
Vol 95 (2) ◽  
Author(s):  
Xiaoqing Li ◽  
Stephan Schönecker ◽  
Jijun Zhao ◽  
Levente Vitos ◽  
Börje Johansson
Keyword(s):  
First Principles ◽  
First Principles Calculations ◽  
Random Alloys

Elastic parameters of paramagnetic iron-based alloys from first-principles calculations

2012 ◽  
Vol 85 (5) ◽  
Author(s):  
Hualei Zhang ◽  
Marko P. J. Punkkinen ◽  
Börje Johansson ◽  
Levente Vitos
Keyword(s):  
First Principles ◽  
First Principles Calculations ◽  
Elastic Parameters ◽  
Iron Based

scholarly journals Pressure Effect on Elastic Constants and Related Properties of Ti3Al Intermetallic Compound: A First-Principles Study

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2015 ◽  
Author(s):  
Xianshi Zeng ◽  
Rufang Peng ◽  
Yanlin Yu ◽  
Zuofu Hu ◽  
Yufeng Wen ◽  
...  
Keyword(s):  
Intermetallic Compound ◽  
Debye Temperature ◽  
Elastic Constants ◽  
First Principles ◽  
Density Functional ◽  
Mechanical Stability ◽  
Theoretical Data ◽  
Young’S Moduli ◽  
Anisotropic Factor ◽  
Isotropic Pressure

Using first-principles calculations based on density functional theory, the elastic constants and some of the related physical quantities, such as the bulk, shear, and Young’s moduli, Poisson’s ratio, anisotropic factor, acoustic velocity, minimum thermal conductivity, and Debye temperature, are reported in this paper for the hexagonal intermetallic compound Ti 3 Al. The obtained results are well consistent with the available experimental and theoretical data. The effect of pressure on all studied parameters was investigated. By the mechanical stability criteria under isotropic pressure, it is predicted that the compound is mechanically unstable at pressures above 71.4 GPa. Its ductility, anisotropy, and Debye temperature are enhanced with pressure.

Importance of Thermally Induced Magnetic Excitations in First-Principles Simulations of Elastic Properties of Transition Metal Alloys

2012 ◽  
Vol 190 ◽  
pp. 291-294
Author(s):  
Igor A. Abrikosov ◽  
Marcus Ekholm ◽  
Alena V. Ponomareva ◽  
Svetlana A. Barannikova
Keyword(s):  
Transition Metal ◽  
Elastic Properties ◽  
Ground State ◽  
First Principles ◽  
Magnetic Moments ◽  
Metal Alloys ◽  
Face Centered Cubic ◽  
Magnetic Ground State ◽  
Magnetic Excitations ◽  
Transition Metal Alloys

We demonstrate the importance of accounting for the complex magnetic ground state and finite temperature magnetic excitations in theoretical simulations of structural and elastic properties of transition metal alloys. Considering Fe72Cr16Ni12face centered cubic (fcc) alloy, we compare results of first-principles calculations carried out for ferromagnetic and non-magnetic states, as well as for the state with disordered local moments. We show that the latter gives much more accurate description of the elastic properties for paramagnetic alloys. We carry out a determination of the magnetic ground state for fcc Fe-Mn alloys, considering collinear, as well as non-collinear states, and show the sensitively of structural and elastic properties in this system to the detailed alignment between magnetic moments. We therefore conclude that it is essential to develop accurate models of the magnetic state for the predictive description of properties of transition metal alloys.

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