The Mechanics of Cross-Slip in L12 Alloys

1994 ◽  
Vol 364 ◽  
Author(s):  
Georges Saada ◽  
Xiaoli Shi ◽  
Patrick VeyssiÈre Lem
Keyword(s):  
Fine Structure ◽  
Flow Stress ◽  
Cross Slip ◽  
Cube Plane ◽  
Close Analysis ◽  
The Stability ◽  
Dislocation Multiplication

AbstractRelationships between the microstructural organization in Ll2 alloys and the flow stress anomaly are discussed. Attention is paid to the origin of friction on the cube plane, to the stability of Kear-Wilsdorf (KW) locks and to the fine structure of kinks. The difficulty of dislocation multiplication and the easiness of their annihilation are outlined. Directions for a future model of the flow stress anomaly based on a close analysis of the microstructure are given.

Fine structure of the stability diagram and the amplitude of ion oscillation within hyperboloidal mass spectrometers

2002 ◽  
Vol 16 (4) ◽  
pp. 261-263 ◽  
Author(s):  
Ernst P. Sheretov ◽  
Igor V. Philippov ◽  
Tatiana B. Karnav ◽  
Edgar V. Fedosov ◽  
Vladimir W. Ivanov
Keyword(s):  
Fine Structure ◽  
Stability Diagram ◽  
Mass Spectrometers ◽  
The Stability

Angle-Resolved Photoemission Extended Fine Structure Study Of Chemisorbed c(2×2)P/Fe(100): Comparison With Self-Consistent-Field Xα Scattered Wave Calculations

1996 ◽  
Vol 437 ◽  
Author(s):  
W.R.A. Huff ◽  
Y. Chen ◽  
X.S. Zhang ◽  
L.J. Terminello ◽  
F.M. Tao ◽  
...  
Keyword(s):  
Fine Structure ◽  
Linear Prediction ◽  
Spherical Wave ◽  
Scattered Wave ◽  
Interlayer Spacing ◽  
Structure Study ◽  
Consistent Field ◽  
Close Analysis ◽  
Self Consistent ◽  
Self Consistent Field

AbstractAngle-resolved photoemission extended fine structure (ARPEFS) was used to determine the structure of c(2×2)P/Fe(100) for the first time. P 1s core-level photoemission data were collected normal to the (100) surface and 45° off-normal along the [011] direction at room temperature. A close analysis of the auto-regressive linear prediction based Fourier transform and multiple-scattering spherical-wave calculations indicate that the P atoms adsorb in the high-coordination four-fold hollow sites. The P atoms bond 1.02 Å above the first layer of Fe atoms and the Fe-P-Fe bond angle is 140.6°. Additionally, it was determined that there is no expansion of the Fe surface. Self-consistent-field Xα scattered wave calculations were performed for the c(2×2)P/Fe(100) and the c(2×2)S/Fe(100) systems. These independent results are in excellent agreement with this P/Fe structure and the S/Fe structure previously published, confirming the ARPEFS determination that the Fe1-Fe2 interlayer spacing is contracted from the bulk value for S/Fe but not for P/Fe.

The effect of fine structure on the stability of planar vortices

2003 ◽  
Vol 22 (2) ◽  
pp. 179-198 ◽  
Author(s):  
Ian M. Hall ◽  
Andrew P. Bassom ◽  
Andrew D. Gilbert
Keyword(s):  
Fine Structure ◽  
The Stability

scholarly journals Testing the Stability of the Fine Structure Constant in the Laboratory

2009 ◽  
Vol 148 (1-4) ◽  
pp. 267-288 ◽  
Author(s):  
N. Kolachevsky ◽  
A. Matveev ◽  
J. Alnis ◽  
C. G. Parthey ◽  
T. Steinmetz ◽  
...  
Keyword(s):  
Fine Structure ◽  
Structure Constant ◽  
Fine Structure Constant ◽  
The Stability

"The Whole World Is In Uproar": Discourses of Fear, Instability, and Global Change in West German Media, 1977-1980

2007 ◽  
Vol 25 (3) ◽  
pp. 25-41 ◽  
Author(s):  
Maria Stehle
Keyword(s):  
Global Change ◽  
Nation State ◽  
The West ◽  
Western Nation ◽  
Close Analysis ◽  
German Nation ◽  
The Stability ◽  
German Newspapers ◽  
Media Responses

After presenting a brief summary of the events leading up to the German Autumn, this article offers a close analysis of media responses in major German newspapers and magazines in the months following these violent and confusing political developments. It compares these responses to reports in January 1980, where the events of the late 1970s serve as a catalyst for fears of global change. Media articulate these fears about the stability and identity of the West German nation state in increasingly vague and generalized terms and relate them to a global situation that is "out of control." The discussions in this article suggest that these expressed fears reveal tensions, interruptions, and gaps in the conservative fantasy of the secure and prosperous Western nation state.

The Deformation Microstructure in NI3Si Polycrystals Strained Over the Range of Temperature of Flow Stress Anomaly

1988 ◽  
Vol 133 ◽  
Author(s):  
B. Tounsia ◽  
P. Beauchamp ◽  
Y. Mishima ◽  
T. Suzuki ◽  
P. Veysslière
Keyword(s):  
Flow Stress ◽  
Slip System ◽  
Room Temperature ◽  
Peak Temperature ◽  
Effect Of Temperature ◽  
Screw Dislocations ◽  
Thermally Activated ◽  
Cube Plane ◽  
Octahedral Slip ◽  
Increasing Temperature

ABSTRACTIn order to correlate the flow stress anomaly of Ni3Si with dislocation properties, a weakbeam study ofpolycrystalline samples deformed between ambient and the peak temperature was carried out. Samples with two extreme Ni/Si ratios were tested.The most frequently activated slip system changes progressively from octahedral to cubic with increasing temperature. The transformation of superdislocations into Kear-Wilsdorf configurations gives rise to screw dislocations that are rectilinear only after deformation at room temperature. The effect of temperature is to gradually promote bending of Kear-Wisdorf configurations in the cube plane, from a few nanometers at 230°C to several tenths of micrometers at intermediate temperature. Cube slip begins to be massively activated a little below the peak temperature. It is suggested that the flow stress anomaly is controlled by progressive exhaustion of octahedral slip by thermally-activated expansion of superdislocations on the cube cross-slip plane.

scholarly journals Dark energy and equivalence principle constraints from astrophysical tests of the stability of the fine-structure constant

2015 ◽  
Vol 2015 (08) ◽  
pp. 047-047 ◽  
Author(s):  
C.J.A.P. Martins ◽  
A.M.M. Pinho ◽  
R.F.C. Alves ◽  
M. Pino ◽  
C.I.S.A. Rocha ◽  
...  
Keyword(s):  
Fine Structure ◽  
Dark Energy ◽  
Equivalence Principle ◽  
Structure Constant ◽  
Fine Structure Constant ◽  
The Stability

Dislocation Multiplication by Single Cross Slip for FCC at Submicron Scales

2013 ◽  
Vol 30 (4) ◽  
pp. 046103 ◽  
Author(s):  
Yi-Nan Cui ◽  
Zhan-Li Liu ◽  
Zhuo Zhuang
Keyword(s):  
Cross Slip ◽  
Single Cross ◽  
Dislocation Multiplication

Plastic Flow of L12 Ordered Alloys

1984 ◽  
Vol 39 ◽  
Author(s):  
D. P. Pope ◽  
V. Vitek
Keyword(s):  
Flow Stress ◽  
Plastic Strain ◽  
Dislocation Core ◽  
Uniaxial Stress ◽  
Cross Slip ◽  
Slip Model ◽  
Unusual Behavior ◽  
Solid Solution Strengthening ◽  
Ordered Alloys ◽  
The Cross

ABSTRACTThe flow stress of many L12 ordered alloys has a very unusual temperature dependence: the flow stress increases with increasing temperature. This unusual behavior is related to the nature of dislocation dissociation and core structure. The flow stress increase is the result of thermally activated cross slip of [101] screw dislocations to the (010) plane which is accompanied by a transformation of the dislocation core from a glissile to a sessile form. Thus dislocations which are mobile on (111) planes become immobile after cross-slip into (010) planes. The dependence of the flow stress on temperature, orientation and sense of the applied uniaxial stress will be discussed in the light of this cross slip model for Ni3Al, Ni3Ga and for γ/γ′ nickel base superalloys.The response of Ni3Al to cyclic plastic strains (plastic strain controlled fatigue) will also be shown to be in accord with the cross slip model. The mean stress in such a test becomes compressive or tensile, depending on the orientation of the sample, even though the net plastic strain is zero after each cycle.The strengthening of Ni3Al by ternary additions will also be discussed. It will be shown that ordinary solid solution strengthening models are not applicable but that the cross slip model can also be applied.Finally, it will be shown that dislocation core simulation studies predict that there should also be a class of L12 ordered alloys that show a “normal” flow stress-temperature behavior, i.e., the flow stress increases at low temperatures. The results of our studies on Pt3Al will be used to illustrate this behavior.

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