First principles calculation of occupancy, bonding characteristics and alloying effect of Cr, Mo, Ni in bulk α-Fe?

文平,; 李春福,; 赵毅,; 张凤春,; 童丽华,

doi:10.7498/aps.63.197101

Cited by 11 publications

(3 citation statements)

References 30 publications

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“…The wider the pseudogap, the stronger the covalent bond. [ 58 ] Table 7 shows the size of the pseudogap of the density of states of these four MEAs. It can be seen from the table that the order of the pseudogap of these four alloys is TiNbTaHf>TiNbHfZr>TiHfTaZr>TiNbTaZr.…”

Section: Resultsmentioning

confidence: 99%

Effect of Hf Substitution on Mechanical Properties of TiNbTaZr Medium Entropy Alloy by First Principle Calculation

Chen,

Li,

Liu

et al. 2023

Cryst. Res. Technol.

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In order to explore the mechanism of mechanical properties of TiNbTaZr after non‐Ti elements are replaced by Hf from the perspective of electronic structure. Analyzing the structural characteristics of TiNbTaZr, TiHfNbZr, TiNbHfZr, and TiNbTaHf medium entropy alloys by solid solution characteristic parameters. Establishing the corresponding structural models and dealing with the first‐principles calculations. By analyzing the binding energy and formation enthalpy, it is determined that these four alloys are metastable β‐Ti alloys of disordered solid solution, and the thermodynamic stability of the structure is confirmed by phonon spectrum. The elastic constants, Poisson's ratio, and hardness of these four alloys show that the strength of Hf‐containing alloys is improved and the ductility is slightly reduced compared with TiNbTaZr. From the analysis of population and density of states, it is concluded that the reason for the above phenomenon is that Hf will cause the improvement of bonding stability and covalency of alloy materials, thus promoting the improvement of theoretical strength of alloys. TiNbHfZr exhibits excellent properties of high strength and low elastic modulus and has good ductility.

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Section: Resultsmentioning

confidence: 99%

Effect of Hf Substitution on Mechanical Properties of TiNbTaZr Medium Entropy Alloy by First Principle Calculation

Chen,

Li,

Liu

et al. 2023

Cryst. Res. Technol.

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“…By comparison, it was found that the energy of each corrosive ion was the lowest at the bridge site of the TiO 2 (100) surface. If the energy of the adsorption system were more negative, its structure would be more stable [16]. Therefore, it can be determined that all of the best adsorption sites of Cl − , HS − , S 2− , HCO 3 − , and CO 3 2− on the TiO 2 (100) surface were bridge sites.…”

Section: Stable Adsorption Modelmentioning

confidence: 99%

Adsorption Characteristics between Ti Atoms of TiO2(100) and Corrosive Species of CO2-H2S-Cl− System in Oil and Gas Fields

Zhu

Wang

et al. 2023

Materials

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The service environment of OCTG (Oil Country Tubular Goods) in oil and gas fields is becoming more and more severe due to the strong affinity between ions or atoms of corrosive species coming from solutions and metal ions or atoms on metals. While it is difficult for traditional technologies to accurately analyze the corrosion characteristics of OCTG in CO2-H2S-Cl− systems, it is necessary to study the corrosion-resistant behavior of TC4 (Ti-6Al-4V) alloys based on an atomic or molecular scale. In this paper, the thermodynamic characteristics of the TiO2(100) surface of TC4 alloys in the CO2-H2S-Cl− system were simulated and analyzed by first principles, and the corrosion electrochemical technologies were used to verify the simulation results. The results indicated that all of the best adsorption positions of corrosive ions (Cl−, HS−, S2−, HCO3−, and CO32−) on TiO2(100) surfaces were bridge sites. A forceful charge interaction existed between Cl, S, and O atoms in Cl−, HS−, S2−, HCO3−, CO32−, and Ti atoms in TiO2(100) surfaces after adsorption in a stable state. The charge was transferred from near Ti atoms in TiO2 to near Cl, S, and O atoms in Cl−, HS−, S2−, HCO3−, and CO32−. Electronic orbital hybridization occurred between 3p5 of Cl, 3p4 of S, 2p4 of O, and 3d2 of Ti, which was chemical adsorption. The effect strength of five corrosive ions on the stability of TiO2 passivation film was S2− > CO32− > Cl− > HS− > HCO3−. In addition, the corrosion current density of TC4 alloy in different solutions containing saturated CO2 was as follows: NaCl + Na2S + Na2CO3 > NaCl + Na2S > NaCl + Na2CO3 > NaCl. At the same time, the trends of Rs (solution transfer resistance), Rct (charge transfer resistance), and Rc (ion adsorption double layer resistance) were opposite to the corrosion current density. The corrosion resistance of TiO2 passivation film to corrosive species was weakened owing to the synergistic effect of corrosive species. Severe corrosion resulted, especially pitting corrosion, which further proved the simulation results mentioned above. Thus, this outcome provides the theoretical support to reveal the corrosion resistance mechanism of OCTG and to develop novel corrosion inhibitors in CO2-H2S-Cl− environments.

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“…在这些计算模拟方法中, 第一性原理方法能够对掺杂体系的电子结构、力学性能、成键形态、结构稳定性等进行准确模拟, 从而在原子尺度上实现对缺陷元素和氢元素相互作用的理论诠释. 例如, Chatterjee等 [8] 对FeNi合金在Ni元素不同掺杂浓度、不同掺杂位置下的相对稳定性进行了基于DFT+U的计算分析, 发现Ni 掺杂bcc结构Fe的稳定性关键取决于Ni在Fe基体中的分布状态; Xiong等 [9] 通过计算H原子在 bcc-Fe(1 0 0)表面以及不同元素掺杂后表面的吸附和渗透过程, 指出Mn, Cr, V元素掺杂形成合金表面后能降低H原子的吸附稳定性与覆盖率, 是抑制H元素渗透的理想合金掺杂元素. 文平等 [10] 探讨了合金钢中Cr, Mo, Ni原子与铁素体α-Fe(C) 的作用, 发现Cr能够强化晶胞并增强体系的稳定性, 对增强铁素体机械性能帮助较大; Mo虽然能强化晶胞, 但其强烈的反键作用却使晶胞的稳定性大大降低.…”

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First principles and molecular dynamics simulations of effect of dopants on properties of high strength steel for hydrogen storage vessels

Hu,

Li,

Zhang

2024

Acta Phys. Sin.

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High-pressure gaseous hydrogen storage is an important way of hydrogen energy storage and transport at present, while high-strength steel material is one of the main materials used for hydrogen storage vessels. However, their internal doping elements and inherent defects often lead to a decrease in their mechanical properties, which reduces the pressure-bearing capacity and storage life of the vessel. At present, the influence mechanism of doping elements on the mechanical properties of high-strength steels is still unclear. This paper, therefore, applies a first-principles approach to study the influence of elemental doping (Cr, Mn, Mo, As, Sb, Bi, Sn, Pb) on the mechanical properties of Fe single crystals and Fe-C systems. Results show that Mn doping among the above elements increases the elastic modulus, bulk modulus and shear modulus compared with that of pure Fe, while the remaining elements decrease them, with the non-transition metal elements having a greater effect on the three moduli than the transition metal elements. Electronic structure analysis shows that the transition metal elements have better compatibility with the Fe lattice. Molecular dynamics results further show that the injection of H atoms significantly disrupts the lattice ordering of the Fe polycrystalline doped system with C, Cr, and Mn elements, while the doping of Cr elements can significantly enhance the dislocation density of the system. In summary, this paper explores the effects of doping elements on the mechanical properties of single-crystal and polycrystalline Fe, which is of strong guiding significance for the mechanistic study of the effects of doping and defects on the strength of Fe-based materials.

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First principles calculation of occupancy, bonding characteristics and alloying effect of Cr, Mo, Ni in bulk α-Fe?

Cited by 11 publications

References 30 publications

Effect of Hf Substitution on Mechanical Properties of TiNbTaZr Medium Entropy Alloy by First Principle Calculation

Effect of Hf Substitution on Mechanical Properties of TiNbTaZr Medium Entropy Alloy by First Principle Calculation

Adsorption Characteristics between Ti Atoms of TiO2(100) and Corrosive Species of CO2-H2S-Cl− System in Oil and Gas Fields

First principles and molecular dynamics simulations of effect of dopants on properties of high strength steel for hydrogen storage vessels

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