Deformation and Dislocation Structure of Ti3AI Single Crystals

1990 ◽  
Vol 186 ◽  
Author(s):  
Y. Minonishi
Keyword(s):  
Slip System ◽  
Single Crystals ◽  
Yield Stress ◽  
Dislocation Structure ◽  
Deformation Characteristics ◽  
Prism Slip ◽  
Pyramidal Slip ◽  
Pure Metals

AbstractDeformation characteristics of Ti3A1 single crystals has been examined as a function of orientation and temperature. This paper mainly describes the result of compression along the c axis. In this orientation, the yield stress increases from 300 to 1100K, decreasing rapidly thereafter. The slip system activated are {1121}<1126> and dislocations observed are nearly of edge character. The anomaly is discussed in comparison with the behavior of other intermetallics and pure metals. An important role this pyramidal slip plays in polycrystalline ductility of Ti3Al is shown in the light of the briefly described results of the prism slip.

Tensile Deformation Behavior of Magnesium Single Crystals with Different Yttrium Concentrations

2021 ◽  
Vol 1016 ◽  
pp. 516-521
Author(s):  
Tomohiro Hanada ◽  
Masayuki Tsushida ◽  
Hiromoto Kitahara ◽  
Shinji Ando
Keyword(s):  
Slip System ◽  
Single Crystals ◽  
Yield Stress ◽  
Tensile Deformation ◽  
Tensile Tests ◽  
Second Order ◽  
Pyramidal Slip ◽  
Tensile Deformation Behavior ◽  
Yttrium Addition ◽  
Critical Resolved Shear Stress

Tensile tests of Mg-Y single crystals with different yttrium concentrations: 0.07 and 0.3 at.% were carried out to investigate effects of yttrium on pyramidal <c+a> slip system. In Mg-0.07at%Y alloy single crystals, {11 2}< 23> second order pyramidal <c+a> slip was activated and yield stress increased, compared to pure Mg single crystals. On other hand, in Mg-0.3at%Y alloy single crystals, {10 1}< 23> first order pyramidal <c+a> slip was activated and yield stress increased, compared to Mg-0.07at%Y alloy single crystals. The change in slip system by yttrium addition would be caused by increasing critical resolved shear stress (CRSS) for second order pyramidal slip.

Effect of Antiphase Domain Boundaries on Prism Slip in Ti3Al Single Crystals

2002 ◽  
Vol 753 ◽  
Author(s):  
Y. Koizumi ◽  
Y. Minamino ◽  
N. Tsuji ◽  
T. Nakano ◽  
Y. Umakoshi
Keyword(s):  
Single Crystal ◽  
Single Crystals ◽  
Yield Stress ◽  
Dislocation Structure ◽  
Antiphase Domain ◽  
Prism Slip ◽  
Domain Boundaries ◽  
Antiphase Domains

ABSTRACTEffect of antiphase domain boundaries (APDBs) on yielding and dislocation structure were investigated in Ti3Al single crystals oriented for prism slip. The yield stress greatly depended on the size of antiphase domains (APDs). The yield stress of Ti3Al with the average APD size of 35nm was about six times higher than that of Ti3Al without APDB. Single dislocations (isolated superpartial dislocations) were observed in the deformed Ti3Al single crystal with APD sizes smaller than 100nm, while superdislocation pairs were observed in those with larger APDs. The mechanism of the interaction between the prism dislocations and APDBs is discussed.

Parameters of Dislocation Structure and Work Hardening of Ni3Ge

2004 ◽  
Vol 842 ◽  
Author(s):  
N. A. Koneva ◽  
Yu.V. Solov'eva ◽  
V. A. Starenchenko ◽  
E. V. Kozlov
Keyword(s):  
Single Crystals ◽  
Yield Stress ◽  
Dislocation Structure ◽  
Temperature Anomaly ◽  
Friction Stress ◽  
Orientation Dependence ◽  
Compression Tests ◽  
Quantitative Measurements ◽  
Different Temperatures ◽  
Scalar Dislocation Density

ABSTRACTOrientation dependence of the yield stress temperature anomaly in Ni3Ge single crystals with the L12 structure was investigated during compression tests. The measurements were carried out in the 4.2 K-1000 K temperature interval for two orientations of single crystals, [001] and [234]. The dislocation structure was studied by TEM. Quantitative measurements of different parameters of dislocation structure were carried out. The values of the scalar dislocation density, ρ, were determined for different temperatures in the deformation interval from the yield stress up to fracture. Temperature dependence of the friction stress τF (T) and the interdislocation interaction parameter α(T) were also obtained. The change in the fraction of straight dislocations as a function of temperature was analyzed.

Deformation Behavior of Magnesium Single Crystals in C-Axis Compression

2007 ◽  
Vol 345-346 ◽  
pp. 129-132 ◽  
Author(s):  
Takaaki Kitahara ◽  
Shinji Ando ◽  
Masayuki Tsushida ◽  
Hiromoto Kitahara ◽  
Hideki Tonda
Keyword(s):  
Fracture Surface ◽  
Single Crystals ◽  
Yield Stress ◽  
Deformation Behavior ◽  
Anomalous Temperature Dependence ◽  
Anomalous Temperature ◽  
Pyramidal Slip ◽  
Axis Compression ◽  
General Deformation ◽  
Increasing Temperature

In general, deformation behavior of magnesium in compression is different from tensile. To investigate deformation behavior of magnesium single crystals, c-axis compression was performed. The crystals were yielded by second order pyramidal slip, and the yield stress shows anomalous temperature dependence (increased with increasing temperature) between 203K and 293K. Yield stress of c-axis compression is bigger than that of a-axis tensile. {10-13} twin and {11-24} twin occurred at 77293K and 77473K respectively. Fracture surface at 77293K was {11-24} and at 473K was {11-22}.

Fine Structures of the Pyramidal Slip Dislocations in Ti3Al Single Crystals at Temperatures of the Yield Stress Anomaly

1998 ◽  
Vol 552 ◽  
Author(s):  
Yasuhide Minonishi
Keyword(s):  
Single Crystals ◽  
Yield Stress ◽  
Basal Plane ◽  
Extreme Temperature ◽  
Marked Change ◽  
The Other ◽  
Antiphase Boundaries ◽  
Dislocation Configuration ◽  
Pyramidal Slip ◽  
Fine Structures

ABSTRACTThe <1126>(1121) pyramidal slip in Ti3Al shows the so-called yield stress anomaly. A marked change in dislocation configuration is observed in the temperature range concerned; dislocations observed at the lowest temperature of the range, −70°C, are ordinary pairs of edge c+a/2 superpartial dislocations coupled by antiphase boundaries (APBs) while at the other extreme temperature 700°C, pairs of unlike superpartials coupled by APBs are observed. The change in dislocation configurations is interpreted as resulting from immobilization of edge c+a/2 superpartial segments by climb dissociation onto the basal plane.

Temperature Dependence of Deformation Behavior in Magnesium and Magnesium Alloy Single Crystals

2007 ◽  
Vol 345-346 ◽  
pp. 101-104 ◽  
Author(s):  
Shinji Ando ◽  
Naoharu Harada ◽  
Masayuki Tsushida ◽  
Hiromoto Kitahara ◽  
Hideki Tonda
Keyword(s):  
Magnesium Alloy ◽  
Temperature Dependence ◽  
Single Crystals ◽  
Yield Stress ◽  
Deformation Behavior ◽  
Pure Magnesium ◽  
Pyramidal Slip ◽  
Increasing Temperature ◽  
Zn Alloy ◽  
Active Slip

It is important to research activation of the slip systems in magnesium crystals to understand deformation behavior of magnesium. In this study, pure magnesium, Mg-7.0at%Li and Mg-0.1at%Zn single crystals were stretched in the [11-20] direction in the range of 77K to 573K to investigate the deformation behavior by non-basal slip. The active slip system was investigated by the observation of slip bands, etch pit bands and dislocations by TEM. {11-22} <-1-123> second order pyramidal slip is activated in all magnesium and magnesium alloy single crystals, and its yield stress shows anomalous temperature dependence in the range from 77K to 293K, however, the yields stress decreased rapidly with increasing temperature above 293K. The yield stress due to the pyramidal slip in Mg-Li and Mg-Zn alloy were lower than that of pure magnesium about 20MPa whereas the stress of Mg-Zn at 77K was about two times higher than pure magnesium.

scholarly journals Dislocation Structure in Ti3Al Single Crystals Cyclically Deforming by Prism Slip

Materia Japan ◽  
1998 ◽  
Vol 37 (5) ◽  
pp. 363-363
Author(s):  
Yukichi Umakoshi ◽  
Takayoshi Nakano ◽  
Yuichirou Koizumi
Keyword(s):  
Single Crystals ◽  
Dislocation Structure ◽  
Prism Slip
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