Polarization of plastic deformation modes in polysynthetically twinned TiAl crystals

2003 ◽  
Vol 18 (3) ◽  
pp. 702-708 ◽  
Author(s):  
V. Paidar ◽  
K. Kishida ◽  
M. Yamaguchi
Keyword(s):  
Plastic Deformation ◽  
Deformation Mode ◽  
Deformation Twinning ◽  
Additional Stress ◽  
Burgers Vector ◽  
Stress Increase ◽  
Loading Direction ◽  
Deformation Modes ◽  
Lamellar Interfaces

Polarization of deformation twinning (its propagation in a certain sense but not in the opposite one) is taken for granted. However, the same phenomenon can occur for a superdislocation glide as well, as is demonstrated in this paper. The consequences for plastic deformation of polysynthetically twinned TiAl crystals with the lamellar interfaces parallel to the loading direction are discussed. It is not the interface itself that is an obstacle for propagating deformation but also the fact that a deformation mode with the parallel Burgers vector cannot be activated in the neighboring lamella due to the directionality of superdislocation motion leading to additional stress increase.

Microstructure Evolution of Near Gamma TiAl Intermetallic under Tensile Impact Loadings at High Temperatures

2010 ◽  
Vol 146-147 ◽  
pp. 1553-1556
Author(s):  
Yu Wang ◽  
Xiang Zan ◽  
Yue Hui He ◽  
Yang Wang
Keyword(s):  
Strain Rate ◽  
Microstructure Evolution ◽  
Deformation Mode ◽  
Deformation Twinning ◽  
Stacking Fault ◽  
Effect Of Temperature ◽  
Dislocation Slip ◽  
Tem Analysis ◽  
Dynamic Loadings ◽  
Deformation Modes

The effect of temperature and strain rate on the mechanical behavior and microstructure evolution of Near Gamma Ti-46.5Al-2Nb-2Cr (NG TiAl) was investigated at temperatures ranging from room temperatures to 840 under strain rates of 0.001, 320, 800 and 1350s-1. The TEM analysis indicated that deformation twinning and stacking fault are the main deformation modes under dynamic loadings and dislocation slip is another important deformation mode under quasi-static loadings. The density of deformation twinning and/or stacking fault increases with the increased temperature and strain rate.

Deformation Twinning, Slip, Martensite Formation and Crack Inhibition in the B2-Type Zr50Pd35Ru15 Alloy

1991 ◽  
Vol 246 ◽  
Author(s):  
R.M. Waterstrat ◽  
L.A. Bendersky ◽  
R. Kuentzler
Keyword(s):  
Crystal Structure ◽  
Plastic Deformation ◽  
Room Temperature ◽  
Deformation Mode ◽  
Deformation Twinning ◽  
Mechanical Twinning ◽  
Dislocation Slip ◽  
Slip Mode ◽  
Martensite Formation ◽  
Additional Mode

AbstractEnhanced room temperature toughness of the Zr50Pd35Ru15B2 phase alloy was found to be a result of the activation of an additional deformation mode besides the b=[001] dislocation slip mode - {114}-type mechanical twinning. The twinning is a true one, i.e. there is no change in the ordered crystal structure. Another additional mode of plastic deformation, expected for more Pd rich alloys, is the formation of stress-induced martensite. The martensite was found to have a CrBtype structure.

The Role of Texture, Temperature and Strain Rate in the Activity of Deformation Twinning

2005 ◽  
Vol 495-497 ◽  
pp. 1037-1042 ◽  
Author(s):  
Donald W. Brown ◽  
Sean R. Agnew ◽  
S.P. Abeln ◽  
W.R. Blumenthal ◽  
Mark A.M. Bourke ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Deformation Mode ◽  
Relative Activity ◽  
Deformation Twinning ◽  
Underlying Structure ◽  
Cubic Metals ◽  
Pyramidal Slip ◽  
Crystallographic Symmetry

Plastic deformation in cubic metals is relatively simple due to the high crystallographic symmetry of the underlying structure. Typically, one unique slip mode can provide arbitrary deformation. This is not true in lower symmetry hexagonal metals, where prismatic and basal slip (the usual favored modes) are insufficient to provide arbitrary deformation. Often, either pyramidal slip and/or deformation twinning must be activated to accommodate imposed plastic deformation. The varied difficulty of activating each of these deformation mechanisms results in a highly anisotropic yield surface and subsequent mechanical properties. Further, the relative activity of each deformation mode may be manipulated through control of the initial crystallographic texture, opening new opportunities for the optimization of mechanical properties for a given application.

Influence Study of the Plastic Deformation Mode on the Micro-Indentation Mechanical Properties for the Pure Molybdenum

2021 ◽  
Vol 894 ◽  
pp. 39-43
Author(s):  
Jiang Li ◽  
Peng Fa Feng ◽  
Fu Guo Li ◽  
Qing Hua Li ◽  
Lin Lin Duan
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Powder Metallurgy ◽  
Deformation Mode ◽  
Indentation Hardness ◽  
Pure Molybdenum ◽  
Apparent Modulus ◽  
Deformation Instability ◽  
Deformation Modes ◽  
Micro Indentation

Four different plastic deformation modes of pure molybdenum in powder metallurgy were studied, including single tensile, single torsion, tensile-torsion and compressive-torsion. Then the influence of these four plastic deformation modes on the micro-mechanical properties of pure molybdenum in powder metallurgy was studied by the micro-indentation method. The results show that the accumulated strain before deformation instability or fracture of the studied material caused by different plastic deformation modes is different, while showing a regular variation. And the mean indentation hardness along the radial direction of the sample also change regularly, which results in different strengthening effects on the molybdenum material itself. The damage inside the deformed material will cause the apparent modulus of elasticity measured by micro-indentation to decrease significantly.

Deformation of Polysynthetically Twinned (PST) TiAl Crystals at High Strain Rate and High Temperature

1996 ◽  
Vol 460 ◽  
Author(s):  
Zhe Jin ◽  
George T. Gray ◽  
Masaharu Yamaguchi
Keyword(s):  
High Temperature ◽  
High Strain ◽  
Deformation Mode ◽  
Dislocation Slip ◽  
Ordinary Dislocation ◽  
Mode 2 ◽  
Lamellar Interface ◽  
Deformation Modes ◽  
Loading Axis ◽  
Lamellar Interfaces

ABSTRACTDeformation microstructures in a 45°<321> oriented (the lamellar interface was tilted 45° from the loading axis about the <321> direction in the lamellar interface) poly synthetically twinned (PST) TiAl crystal deformed in compression at 3000 s-1 and 800 °C was studied. Deformation of this PST crystal is characterized as follows: 1) Deformation of domains [III] and [IV] is dominated by 1/6 [112] parallel twinning (twinning parallel to lamellar interfaces). Ordinary dislocations observed in these domains are found to be a complementary deformation mode. 2) Deformation of domains [II], [V] and [VI] is controlled by a 1/2<110] ordinary dislocation slip. Complementary deformation modes in these domains are ordinary dislocation slip, superdislocation slip and cross-twinning. 3) Domain [I] is not deformed after the specimen deforms up to ∼7% strain.

Compression deformation behavior of Zircaloy-4 alloy changing with activated twinning type at ambient temperature: experiment and modeling

2016 ◽  
Vol 49 (3) ◽  
pp. 987-996 ◽  
Author(s):  
Hongjia Li ◽  
Wupeng Cai ◽  
Zhijian Fan ◽  
Xuefei Huang ◽  
Yandong Wang ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Ambient Temperature ◽  
Deformation Behavior ◽  
Texture Evolution ◽  
Deformation Mode ◽  
Deformation Twinning ◽  
Rolled Plate ◽  
Strain Partitioning ◽  
Stress Strain ◽  
Plastic Deformation Behavior

It is widely accepted that twinning is important for the plastic deformation of zirconium alloys, although the corresponding roles of different types of twinning are rarely discussed. Here, the deformation behavior of Zircaloy-4 alloy at ambient temperature under compression along the rolling, transverse and normal directions of the rolled plate is studied by examination of macroscopic stress–strain curves, texture evolution andin situlattice strain, combined with elastic–plastic self-consistent simulation. It is concluded that tensile twinning {10\overline 12}〈10\overline 11〉, tensile twinning {11\overline 21}〈11\overline 26〉 and compressive twinning {11\overline 22}〈11\overline 2\overline 3〉 are the main deformation twinning types for compression along the three principal directions. A change in the activated twinning type induces differences in the plastic deformation mode and the stress/strain partitioning between parent and child grains. The work provides insight into the effects of deformation twinning on the plastic deformation behavior of Zircaloy-4 alloy.

Molecular Dynamics Simulations of Orientation Effects During Tension, Compression, and Bending Deformations of Magnesium Nanocrystals

2015 ◽  
Vol 82 (10) ◽  
Author(s):  
Haidong Fan ◽  
Jaafar A. El-Awady
Keyword(s):  
Molecular Dynamics ◽  
Uniaxial Tension ◽  
Uniaxial Compression ◽  
Deformation Mode ◽  
Dislocation Slip ◽  
Pure Bending ◽  
Axis Orientation ◽  
Orientation Effects ◽  
Loading Direction ◽  
Deformation Modes

The deformation modes in magnesium nanocrystals during uniaxial tension, uniaxial compression, and pure bending are investigated using molecular dynamics (MD) simulations at room temperature. For each loading condition, the crystal orientation effects are studied by increasing the crystal c-axis orientation angle θ relative to the loading direction from 0 deg to 90 deg by a 15 deg increment. The simulation results reveal a number of different deformation modes and an obvious tension–compression asymmetry in magnesium nanocrystals. As the c-axis is rotated away from the tension loading direction, the deformation mode at yielding changes from tension twinning (θ ≤ 45 deg) to compression twinning (θ > 45 deg). For compression loading, yielding is dominated by only dislocation slip on the pyramidal (θ < 15 deg), basal (15 deg < θ < 60 deg) and prismatic (θ > 60 deg) planes. The nucleation stress in general decreases with increasing θ for both uniaxial tension and uniaxial compression loadings. For pure bending simulations, the yielding is mostly controlled by the weaker deformation mode between the compressive and tensile sides. The bending nucleation stress also decreases as the c-axis deviates away from the loading direction.

deformation twinning in pure Ti during dynamic plastic deformation

2012 ◽  
Vol 541 ◽  
pp. 190-195 ◽  
Author(s):  
Feng Xu ◽  
Xiyan Zhang ◽  
Haitao Ni ◽  
Qing Liu
Keyword(s):  
Plastic Deformation ◽  
Deformation Twinning ◽  
Dynamic Plastic Deformation

Plastic Deformation of Approximants: Dislocations vs. Phason Lines

1998 ◽  
Vol 553 ◽  
Author(s):  
H. Klein ◽  
M. Feuerbacher ◽  
P. Schall ◽  
K. Urban
Keyword(s):  
Plastic Deformation ◽  
High Temperature ◽  
Single Crystals ◽  
Periodic Lattice ◽  
Length Scale ◽  
Relative Importance ◽  
Line Lattice ◽  
Burgers Vector ◽  
Mechanisms Of Plastic Deformation

AbstractDeformation experiments were performed on single crystals of the ξ-AIPdMn approximant in bending geometry at high temperature. Two different mechanisms of plastic deformation are shown to exist in this phase: one based on dislocations and another novel mechanism based on the motion of phason lines. Burgers vector and line directions of dislocations were determined. Phason lines are shown to build a periodic lattice. The interaction of a dislocation with the phason line lattice results in dislocations on another length scale. This meta-dislocation in the periodic phason line lattice has a Burgers vector of magnitude 165 Å. The relative importance of phason lines and dislocations for the plastic deformation is discussed as a function of the orientation of the sample with respect to the bending geometry.

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