scholarly journals First-Principles Calculations of Oxygen-Dislocation Interaction in Magnesium

Materials ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 116
Author(s):  
Chao Fang ◽  
Jing Zhang ◽  
Ying Huang ◽  
Jianhao Chen
Keyword(s):  
Screw Dislocation ◽  
First Principles ◽  
Dislocation Core ◽  
Prismatic Slip ◽  
Interstitial Oxygen ◽  
First Principles Calculations ◽  
Dislocation Interaction ◽  
Dislocation Glide ◽  
Deformation Behaviors ◽  
Oxygen Atoms

The interaction between interstitial oxygen atoms and <a>-type screw dislocations was investigated via first-principles calculations to elucidate the effect of oxygen solutes on the deformation behaviors of Mg. The results show that repulsive interactions exist between basal screw dislocation cores and oxygen atoms, which would enable the full basal dislocation to bypass the oxygen atoms in the dislocation glide plane through the cross-slip process. This repulsion also increases the resistance to the motion of dissociated basal dislocations. Moreover, the energy of prismatic <a>-type screw dislocation cores is reduced by the presence of oxygen, which would stabilize the screw dislocation core on the prismatic plane, accordingly facilitating the prismatic slip. This information can complement the fundamental knowledge of alloying Mg using interstitial solutes.

scholarly journals Interactions between interstitial oxygen and substitutional niobium atoms in Ti–Nb–O BCC alloys: First-principles calculations

AIP Advances ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 025309
Author(s):  
Chenguang Liu ◽  
Liming Yu ◽  
Yongchang Liu ◽  
Zongqing Ma ◽  
Huijun Li ◽  
...  
Keyword(s):  
First Principles ◽  
Interstitial Oxygen ◽  
First Principles Calculations

First-principles study of PbWO4crystal with interstitial oxygen atoms

2007 ◽  
Vol 204 (3) ◽  
pp. 776-783 ◽  
Author(s):  
Chen Teng ◽  
Liu Ting-Yu ◽  
Zhang Qi-Ren ◽  
Li Fang-Fei ◽  
Yi Zhi-Jun ◽  
...  
Keyword(s):  
First Principles ◽  
Interstitial Oxygen ◽  
First Principles Study ◽  
Oxygen Atoms

scholarly journals Non-glide effects and dislocation core fields in BCC metals

2019 ◽  
Vol 5 (1) ◽  
Author(s):  
Antoine Kraych ◽  
Emmanuel Clouet ◽  
Lucile Dezerald ◽  
Lisa Ventelon ◽  
François Willaime ◽  
...  
Keyword(s):  
First Principles ◽  
Yield Criterion ◽  
Constitutive Models ◽  
Dislocation Core ◽  
First Principles Calculations ◽  
Body Centered Cubic ◽  
Physical Origin ◽  
Bcc Metals ◽  
Energy Models ◽  
Eshelby Inclusion

AbstractA hallmark of low-temperature plasticity in body-centered cubic (BCC) metals is its departure from Schmid’s law. One aspect is that non-glide stresses, which do not produce any driving force on the dislocations, may affect the yield stress. We show here that this effect is due to a variation of the relaxation volume of the $$1/2\langle 111\rangle$$1∕2⟨111⟩ screw dislocations during glide. We predict quantitatively non-glide effects by modeling the dislocation core as an Eshelby inclusion, which couples elastically to the applied stress. This model explains the physical origin of the generalized yield criterion classically used to include non-Schmid effects in constitutive models of BCC plasticity. We use first-principles calculations to properly account for dislocation cores and use tungsten as a reference BCC metal. However, the methodology developed here applies to other BCC metals, other energy models and other solids showing non-glide effects.

Effect of impurity carbon and oxygen atoms on the behavior of hydrogen in vanadium in a fusion environment: A first-principles study

2018 ◽  
Vol 32 (21) ◽  
pp. 1850232
Author(s):  
Juan Hua ◽  
Ying Li ◽  
Yue-Lin Liu
Keyword(s):  
Structural Material ◽  
First Principles ◽  
Nuclear Fusion ◽  
Fusion Reactors ◽  
First Principles Calculations ◽  
Metal Interactions ◽  
First Principles Study ◽  
Free Vacancy ◽  
Oxygen Atoms

We have investigated the effect of impurity X (X = C and O) atoms on the behavior of hydrogen in vanadium, which is an ideal structural material for nuclear fusion reactors, by first-principles calculations. We found that (1) in bulk V, the interaction between an interstitial H atom and an X atom is repulsive, and the interaction with O is much stronger than that with C. (2) The X–vacancy (vac) cluster can act as a center for capturing H in V. The C-vac cluster can trap as many as two H atoms, while the O–vac cluster can capture up to four H atoms. (3) C and O impurities can effectively decrease the trapping energy of a single H atom in a vacancy. The H-trapping energies in the C–vac and O–vac complexes are 0.88 eV and 0.46 eV, respectively, both of which are lower than those in the X-free vacancy. (4) Both H–X and X-metal interactions affect the H solubility in V. The above results provide important information for application of vanadium as a structural material for nuclear fusion tokamaks.

Origin of dramatic oxygen solute strengthening effect in titanium

Science ◽  
2015 ◽  
Vol 347 (6222) ◽  
pp. 635-639 ◽  
Author(s):  
Qian Yu ◽  
Liang Qi ◽  
Tomohito Tsuru ◽  
Rachel Traylor ◽  
David Rugg ◽  
...  
Keyword(s):  
First Principles ◽  
Dislocation Core ◽  
Strengthening Effect ◽  
First Principles Calculations ◽  
Screw Dislocations ◽  
Elastic Fields ◽  
Transmission Electron ◽  
Short Range Repulsion ◽  
Solute Atoms ◽  
Solute Strengthening

Structural alloys are often strengthened through the addition of solute atoms. However, given that solute atoms interact weakly with the elastic fields of screw dislocations, it has long been accepted that solution hardening is only marginally effective in materials with mobile screw dislocations. By using transmission electron microscopy and nanomechanical characterization, we report that the intense hardening effect of dilute oxygen solutes in pure α-Ti is due to the interaction between oxygen and the core of screw dislocations that mainly glide on prismatic planes. First-principles calculations reveal that distortion of the interstitial sites at the screw dislocation core creates a very strong but short-range repulsion for oxygen that is consistent with experimental observations. These results establish a highly effective mechanism for strengthening by interstitial solutes.

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