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.

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.

Size-dependent strain in fivefold twins of gold

2021 ◽  
Vol 77 (1) ◽  
pp. 93-98
Author(s):  
Hao Wu ◽  
Rong Yu ◽  
Jing Zhu ◽  
Wei Chen ◽  
Yadong Li ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
First Principles ◽  
First Principles Calculations ◽  
Geometrical Constraint ◽  
Size Dependent ◽  
Transmission Electron ◽  
Dependent Strain ◽  
Low Dimensional ◽  
Low Dimensional Materials ◽  
Aberration Corrected

Multiple twinned structures are common in low-dimensional materials. They are intrinsically strained due to the geometrical constraint imposed by the non-crystallographic fivefold symmetry. In this study, the strain distributions in sub-10 nm fivefold twins of gold have been analyzed by combining aberration-corrected transmission electron microscopy and first-principles calculations. Bending of atomic planes has been measured by both experiments and calculations, and its contribution to the filling of the angular gap was shown to be size-dependent.

Defect structures of the Cr2O3(11-20) surface: Effect of electron beam irradiation

2021 ◽  
Author(s):  
Wandong Xing ◽  
Haozhi Sha ◽  
Fanyan Meng ◽  
Rong Yu
Keyword(s):  
Electron Microscopy ◽  
First Principles ◽  
Electron Beam Irradiation ◽  
Surface Effect ◽  
Defect Structures ◽  
First Principles Calculations ◽  
Beam Irradiation ◽  
Atomic Structures ◽  
Transmission Electron ◽  
Aberration Corrected

We have revealed the atomic structures and stability of the (11-20) surface of single crystal Cr2O3 combining aberration corrected transmission electron microscopy and first-principles calculations. It is found that the...

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