Observation of Dislocation Glide in Duplex Ti-48at.% Al after Room Temperature Tensile Deformation

2008 ◽  
Vol 1128 ◽  
Author(s):  
Jörg M. K. Wiezorek ◽  
Andreas K. Kulovits
Keyword(s):  
Room Temperature ◽  
Tensile Deformation ◽  
Slip Systems ◽  
Orientation Relation ◽  
Dislocation Glide ◽  
Dislocation Activity ◽  
Pyramidal Slip ◽  
Transmission Electron ◽  
Pile Up ◽  
Fully Lamellar

AbstractIn this study we investigated the deformation behavior of the hexagonal ordered phase α2- Ti3Al in Duplex TiAl under tensile loading. Transmission electron microscopy (TEM) revealed that the orientation relation ships (OR) between α2-Ti3Al and the L10 ordered γ- TiAl phase are very different as compared to the OR common in fully lamellar PST TiAl. We observed deformation related <2c+a> dislocation activity on pyramidal slip systems in the α2-phase during post situ TEM analyses. We rationalize this observation by the possible build up of pile up stresses in γ-TiAl due to the different OR with the α2-Ti3Al phase that can possibly lead to the activation of <2c+a> dislocation activity on pyramidal slip systems with similarly resolved stresses in the α2-Ti3Al phase.

A Study on Tensile Deformation Features of Ni-Based Super-Alloy Prepared by EB-PVD

2011 ◽  
Vol 55-57 ◽  
pp. 251-256
Author(s):  
Li Ma ◽  
Ting Zhang ◽  
Xiao Li ◽  
Zhao Hui Hu
Keyword(s):  
Physical Vapor Deposition ◽  
Large Scale ◽  
Tensile Deformation ◽  
Alloy Sheet ◽  
Dislocation Climb ◽  
Dislocation Glide ◽  
Double Phase ◽  
Transmission Electron ◽  
Deformation Features ◽  
Super Alloy

Large-scale Ni-based super-alloy sheet has been prepared by electron beam physical vapor deposition (EB-PVD). Microstructure and the dislocation structures in the γ-γ′ double phase alloy under different temperature after tensile strain are studied with Transmission electron microscopy (TEM). The results show that the dislocation glide in single slip system and shearing mechanics, the dislocation climb with part shearing, absolute dislocation climb and cross slip, dislocation round are a course of the interacting degree between dislocation and γ′ phase gradually weakened under the tensile temperature from room temperature to high temperature, so as to decrease materials strength and increase plasticity.

scholarly journals Hardening and Strain Localisation in Helium-Ion-Implanted Tungsten

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Suchandrima Das ◽  
Hongbing Yu ◽  
Edmund Tarleton ◽  
Felix Hofmann
Keyword(s):  
Electron Backscatter Diffraction ◽  
Removal Rate ◽  
Strain Localisation ◽  
Slip Step ◽  
Dislocation Glide ◽  
Fusion Neutron ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Helium Ion ◽  
Pile Up

AbstractTungsten is the main candidate material for plasma-facing armour components in future fusion reactors. In-service, fusion neutron irradiation creates lattice defects through collision cascades. Helium, injected from plasma, aggravates damage by increasing defect retention. Both can be mimicked using helium-ion-implantation. In a recent study on 3000 appm helium-implanted tungsten (W-3000He), we hypothesized helium-induced irradiation hardening, followed by softening during deformation. The hypothesis was founded on observations of large increase in hardness, substantial pile-up and slip-step formation around nano-indents and Laue diffraction measurements of localised deformation underlying indents. Here we test this hypothesis by implementing it in a crystal plasticity finite element (CPFE) formulation, simulating nano-indentation in W-3000He at 300 K. The model considers thermally-activated dislocation glide through helium-defect obstacles, whose barrier strength is derived as a function of defect concentration and morphology. Only one fitting parameter is used for the simulated helium-implanted tungsten; defect removal rate. The simulation captures the localised large pile-up remarkably well and predicts confined fields of lattice distortions and geometrically necessary dislocation underlying indents which agree quantitatively with previous Laue measurements. Strain localisation is further confirmed through high resolution electron backscatter diffraction and transmission electron microscopy measurements on cross-section lift-outs from centre of nano-indents in W-3000He.

Tensile Deformation of Magnesium and Magnesium Alloy Single Crystals

2014 ◽  
Vol 783-786 ◽  
pp. 341-345 ◽  
Author(s):  
Shinji Ando ◽  
Atsushi Kodera ◽  
Kazuki Fukushima ◽  
Masayuki Tsushida ◽  
Hiromoto Kitahara
Keyword(s):  
Single Crystals ◽  
Basal Slip ◽  
Tensile Deformation ◽  
Pure Magnesium ◽  
Slip Systems ◽  
Pyramidal Slip ◽  
Higher Temperature ◽  
Von Mises ◽  
Zn Alloy ◽  
Active Slip

According to von-Mises criterion, five kinds of independent slip systems are required for uniform deformation, so it is necessary to activate non-basal slip systems to show good ductility. However, it has not become clear the effect of Zn or Al for non-basal slip systems yet. To investigate deformation behavior of magnesium crystal by non-basal slip and alloying effect for the non-basal slip, pure magnesium and Mg-Al-Zn single crystals were stretched in the [110] direction. While {112}<23> second order pyramidal slip was activated at room temperature in pure magnesium, {101}<23> first order pyramidal slip became active slip at higher temperature. In Mg-Al-Zn alloy single crystal, {101} twin also activated by adding aluminum. These results indicate that active non-basal slip systems and twin in magnesium strongly depend on deformation temperature and alloying elements.

Plastic Deformation of Ti3Al and Ti3Al/TiA1 Polycrystals

1988 ◽  
Vol 133 ◽  
Author(s):  
S. A. Court ◽  
J. P. A. Löfvander ◽  
M. A. Stucke ◽  
P. Kurath ◽  
H. L. Fraser
Keyword(s):  
Electron Microscopy ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Covalent Bonding ◽  
Relative Activity ◽  
Slip Systems ◽  
Dislocation Mobility ◽  
Two Phase ◽  
Influence Of Temperature ◽  
Transmission Electron

ABSTRACTSamples of polycrystalline Ti3Al-base alloys, and a two phase Ti3Al/TiAl mixture have been deformed at room temperature and at elevated temperatures and examined subsequently by transmission electron microscopy in order to determine the influence of temperature and alloy content on the relative activity of the various slip systems. In particular, the detailed influence of covalent bonding on dislocation mobility in Ti3Al has been identified.

Transmission Electron Microscopy of Shock-Deformed Sapphire

1991 ◽  
Vol 49 ◽  
pp. 966-967
Author(s):  
S.-J. Chen
Keyword(s):  
Basal Slip ◽  
Peak Pressure ◽  
Ceramic Materials ◽  
Prismatic Slip ◽  
Slip Systems ◽  
Microstructural Characteristics ◽  
Pyramidal Slip ◽  
Transmission Electron ◽  
Show Evidence ◽  
The Impact

An understanding of the micromechanisms which occur during the shock deformation of hard ceramic materials would be helpful to the development and optimization of these materials in ballistic environments. Previous studies of shock loaded alumina show evidence of plastic flow by basal slip 1/3<110> (0001), basal twinning, pyramidal slip 1/3<010>{113} and prismatic slip 1/3<101>(110), It has also been observed that the grain boundary and interphase material (e. g. glass) play an important role in determining the microstructural characteristics. In order to elucidate the response of different slip systems, as a function of the impact orientation and the magnitude of peak pressure, some experiments with single crystal alumina (sapphire) have been carried out and the preliminary results are presented here.

A Transmission Electron Microscope Study of Hardness Indentations in MoSi2

2000 ◽  
Vol 15 (4) ◽  
pp. 1025-1032 ◽  
Author(s):  
P. H. Boldt ◽  
G. C. Weatherly ◽  
J. D. Embury
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope Study ◽  
Room Temperature ◽  
Slip Systems ◽  
Cavity Model ◽  
Dislocation Loops ◽  
Density Of Dislocations ◽  
Transmission Electron ◽  
Large Rotations ◽  
Transmission Electron Microscope Study

Transmission electron microscopy and electron diffraction were used to study hardness indentations made at room temperature in ⟨001⟩-oriented single crystals of MoSi2. Two families of slip systems, {110}⟨001⟩ and {101}⟨010⟩, were identified. The first system formed ⟨001⟩ dislocation loops by prismatic punching beneath the indenter, while the second system led to large rotations of the crystal lattice beneath the indenter. The lattice rotations were used to estimate the density of dislocations stored in this volume. The results demonstrate that the hardness response of MoSi2 can be explained by the expanding cavity model with most of the plastic accommodation occurring immediately beneath the indenter.

Effect of Iodine and Strontium Ion Implantation on the Microstructure of Cubic Zirconia

2000 ◽  
Vol 647 ◽  
Author(s):  
Sha Zhu ◽  
Lumin Wang ◽  
Shixin Wang ◽  
Rodney C. Ewing
Keyword(s):  
Ion Implantation ◽  
Room Temperature ◽  
Orientation Relation ◽  
Cross Sectional ◽  
Peak Displacement ◽  
Defect Clusters ◽  
Nano Crystalline ◽  
Transmission Electron ◽  
The Matrix ◽  
Strontium Ion

Abstract200 keV iodine and 400 keV strontium ions have been implanted into YSZ in order to study the effects of fission product incorporation in YSZ as an inert fuel matrix. The ion implantation was conducted at room temperature. The ion fluences reached 1×1021 ions/m2 which gives peak displacement damage levels of ~ 290 dpa for I ion implantation and ~ 200 dpa for Sr ion implantation. The peak concentration reaches ~26 at. % for implanted I ions and ~11.6 at.% for Sr ions. Cross-sectional transmission electron microscopy (TEM) was completed to investigate the microstructure changes caused by the implantation. No evidence of amorphization was detected in both samples although a high density of defect clusters was observed by TEM. Cross-sectional TEM revealed formation of iodine containing voids in I- implanted samples and crystalline precipitates of a few tens of nanometers in Sr-implanted samples after annealing of the implanted sample at 1000°C for 0.5 to 2 hours. The void size increased with increasing annealing time. The nano-crystalline precipitates in Sr-implanted YSZ are isometric SrZrO3 (a≅0.41 nm). The orientation relation between the matrix and precipitates, as determined by selected area diffraction pattern, was: [011]YSZ// [111]SrZrO3 and [200]YSZ// [110]SrZrO3.

Experimental Research on Grain Orientation Evolution of Extruded Mg Alloy AZ31B Sheet during Uniaxial Tensile Deformation

2008 ◽  
Vol 32 ◽  
pp. 87-92
Author(s):  
Shi Hong Zhang ◽  
Zhang Gang Li
Keyword(s):  
Room Temperature ◽  
Tensile Deformation ◽  
Tensile Axis ◽  
Mg Alloy ◽  
Uniaxial Tensile ◽  
Slip Systems ◽  
Close Relationship ◽  
Crystal Model ◽  
Ebsd Technique ◽  
Axis Rotation

The orientation rotation in extruded Mg alloy AZ31B sheets during uniaxial tension at room temperature has been investigated using SEM/EBSD technique. According to the experimental results and the calculated results of Sachs crystal model, the quantitative rule of the tensile axis rotation for the grains (parent), and the associated slip systems have been analyzed in detail. The influencing factors of twinning area fraction have also been studied. The results show that the rule of the rotation of tensile axis can be explained by cross slip systems; the grains with different initial orientations exhibit different twinning behaviors; the area fractions of extensive twins have a close relationship with Schmid factors of tensile twinning, and with the angle between c-axis and tensile axis of the grains.

Interactions of Mechanical Twinning and Dislocation Glide with Polytwin-Interfaces in L1o-Ordered Iron-Palladium Intermetallics

2002 ◽  
Vol 753 ◽  
Author(s):  
Huiping Xu ◽  
Jörg Wiezorek
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Room Temperature ◽  
Mechanical Twinning ◽  
Temperature Deformation ◽  
Defect Structures ◽  
Shear Transfer ◽  
Dislocation Glide ◽  
Transmission Electron ◽  
Mechanical Twins

ABSTRACTThe defect structures in polytwinned (PT) FePd have been studied after room temperature deformation by transmission electron microscopy (TEM). Interactions between gliding dislocations and mechanical twins with the {101}-conjugated PT-interfaces have been identified. Based on crystallographic analyses of shear transfer of dislocations and microtwins across the PT-interfaces in FePd boundary reactions have been identified that are consisted with the TEM observations. A model has been proposed, which is suitable to rationalize significant contributions to strain-hardening from these defect-interface interactions in PT-FePd.

scholarly journals Strain hardening recovery mediated by coherent precipitates in lightweight steel

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sung-Dae Kim ◽  
Seong-Jun Park ◽  
Jae hoon Jang ◽  
Joonoh Moon ◽  
Heon-Young Ha ◽  
...  
Keyword(s):  
Strain Hardening ◽  
Mean Free Path ◽  
Aged Alloy ◽  
Slip Systems ◽  
Multiple Slip ◽  
Dislocation Glide ◽  
Transmission Electron ◽  
Planar Dislocation ◽  
Shearing Mechanism ◽  
Strain Hardening Behavior

AbstractWe investigated the effect of κ-carbide precipitates on the strain hardening behavior of aged Fe–Mn-Al-C alloys by microstructure analysis. The κ-carbides-strengthened Fe–Mn-Al-C alloys exhibited a superior strength-ductility balance enabled by the recovery of the strain hardening rate. To understand the relation between the κ-carbides and strain hardening recovery, dislocation gliding in the aged alloys during plastic deformation was analyzed through in situ tensile transmission electron microscopy (TEM). The in situ TEM results confirmed the particle shearing mechanism leads to planar dislocation gliding. During deformation of the 100 h-aged alloy, some gliding dislocations were strongly pinned by the large κ-carbide blocks and were prone to cross-slip, leading to the activation of multiple slip systems. The abrupt decline in the dislocation mean free path was attributed to the activation of multiple slip systems, resulting in the rapid saturation of the strain hardening recovery. It is concluded that the planar dislocation glide and sequential activation of slip systems are key to induce strain hardening recovery in polycrystalline metals. Thus, if a microstructure is designed such that dislocations glide in a planar manner, the strain hardening recovery could be utilized to obtain enhanced mechanical properties of the material.

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