Increase the Deformability of NiCo Single Crystals Using of Electrical Pulse-Like Currents

2012 ◽  
Vol 504-506 ◽  
pp. 143-148 ◽  
Author(s):  
Gregory Gerstein ◽  
Marc Nowak ◽  
Marten Sebastian Bierbaum ◽  
Tatjana Zhuravina ◽  
Mirko Schaper ◽  
...  
Keyword(s):  
Flow Stress ◽  
Single Crystal ◽  
Mechanical Stress ◽  
Single Crystals ◽  
Electrical Pulse ◽  
Short Term ◽  
Nickel Cobalt ◽  
Electrical Pulses ◽  
Deformation Relief ◽  
Cobalt Single Crystals

The effect of short-term electrical pulses on metallic single crystals, with and without the application of external mechanical stresses, was investigated with the aid of deformation reliefs. The nickel-cobalt single crystals were subjected to electrical pulses and subsequently microscopically measured. In doing this, it was established that an electrical pulse without a simultaneously applied mechanical stress, has no influence on the deformation relief. It was possible to show that on loading the single crystal with a mechanical stress, the deformation relief significantly changes even when the stress was markedly below the flow stress.

Rules of Fragmentation and Localization at Aluminium Single Crystal Division during Compression Test

2014 ◽  
Vol 1013 ◽  
pp. 84-90 ◽  
Author(s):  
Ludmila A. Teplyakova ◽  
Irina Bespalova ◽  
Tatyana Kunitsyna
Keyword(s):  
Plastic Deformation ◽  
Single Crystal ◽  
Single Crystals ◽  
Compression Test ◽  
Deformation Process ◽  
Front Face ◽  
Experimental Investigations ◽  
Macroscopic Level ◽  
Plastic Deformation Process ◽  
Deformation Relief

This work presents the results of experimental investigations into deformation relief formed at the faces of aluminium single crystals. The aim of the investigations was to define the rules of macro fragmentation and macro localisation processes in plastic deformation. It was established that for the families of maximum loaded planes {111} in the aluminium single crystals, one can differentiate volumes which aren't limited to the specimen's front face. It is assumed that shearing in these volumes is eased during plastic deformation due to the absence of a reverse stress. Moreover, it is suggested that such volumes are called volumes of eased slip (VES). In addition to this, the role played by the volume of eased slip at the macroscopic level during the plastic deformation process was examined.

Dislocation Dynamics Studied by Mechanical Loss in a Ni3(AI, Ta) Single Crystal at Intermediate Temperatures

1998 ◽  
Vol 552 ◽  
Author(s):  
B. L. Cheng ◽  
E. Carreño-Morelli ◽  
N. Baluc ◽  
J. Bonneville ◽  
R. Schaller
Keyword(s):  
Flow Stress ◽  
Single Crystal ◽  
Single Crystals ◽  
Screw Dislocation ◽  
Strain Amplitude ◽  
Annealing Temperature ◽  
Mobile Dislocation ◽  
Dislocation Dynamics ◽  
Mechanical Spectroscopy ◽  
Mechanical Loss

ABSTRACTDislocation dynamics in Ni3AI intermetallic single crystals has been studied by mechanical spectroscopy between 300 and 700 K. It has been found that in the anomaly domain of the flow stress, which is characteristic of this material, the mechanical loss of predeformed specimens is strongly dependent on strain amplitude, predeformation level, annealing temperature and time. The results can be interpreted as a combination of two phenomena which simultaneously occur as temperature is increased from 300 K to about 500 K: exhaustion of the mobile dislocation segments (superkinks) and pinning of the screw dislocation segments via cross-slip from the (111) onto the (010) planes.

The Temperature and Strain Rate Dependence of the Flow Stress in MoSi2 Single Crystals

1993 ◽  
Vol 322 ◽  
Author(s):  
S.A. Maloy ◽  
T.E. Mitchell ◽  
John J. Petrovic ◽  
A.H. Heuer ◽  
J.J. Lewandowski
Keyword(s):  
Flow Stress ◽  
Slip System ◽  
Strain Rate ◽  
Single Crystal ◽  
Single Crystals ◽  
Stress Exponent ◽  
Deformation Mechanisms ◽  
Strain Rates ◽  
Jump Test ◽  
Stress And Deformation

AbstractThe temperature dependence of the flow stress and deformation mechanisms of single crystal MoSi2 have been determined for compression along three different orientations, [001], [021] and [771], at two different strain rates, 1 × 10−5/s and 1 × 10−4/s, and at temperatures between 900 and 1600°C. The flow stress along [021] is slightly higher than that along [771] while both orientations gave a much lower flow stress than that along [001]. Along [021], slip occurs on the {110} 1/2<111> slip system between 1000 and 1200°C, while at 1300-1400°C, slip occurs on the {013}<100> slip system. Along [771], deformation occurs by the [001]<100> slip system while cross-slip onto {013} and [011] planes is observed at 1000-1300°C except that slip occurs on the {013{1/2<331> slip system at 1000-1100°C for faster strain rates. Along [001], slip occurs on the {013}1/2<331> system at 900-1100°C while slip is observed on the {011} 1/2<111> system at 1300-1600°C. Strain rate jump tests from 1×10−5/s to 5x10−5/s at 1 100°C revealed a stress exponent of 7 along [771] and 20 along [021], while a rate jump test from lx10−5/s to 2x 10−5/s along [001] at 1400°C gave a stress exponent of 3.9.

Stress response by the strain-rate change in binary, stoichiometric Ni3AI single crystal

1996 ◽  
Vol 460 ◽  
Author(s):  
M. Demura ◽  
T. Hirano
Keyword(s):  
Steady State ◽  
Stress Response ◽  
Flow Stress ◽  
Strain Rate ◽  
Single Crystal ◽  
Single Crystals ◽  
Yield Stress ◽  
Temperature Region ◽  
Steady State Flow ◽  
Strain Rate Change

ABSTRACTThe strain-rate dependence of flow stress in single crystals of binary, stoichiometric Ni3Al was studied in the temperature region of the yield stress anomaly. Below 400 K, the steady-state flow stress was found to be independent of strain rate, though it changed temporarily when the strain rate was changed. The strain-rate insensitivity can be explained by assuming that the flow stress is controlled by the multiplication/immobilization of mobile dislocations.

Dislocation structures around SiO2 Particles in aged Cu-Cr-SiO2

1978 ◽  
Vol 36 (1) ◽  
pp. 594-595
Author(s):  
N.J. Long ◽  
M.H. Loretto ◽  
C.H. Lloyd
Keyword(s):  
Flow Stress ◽  
Single Crystals ◽  
Room Temperature ◽  
Thin Foil ◽  
Age Hardening ◽  
Dispersion Strengthening ◽  
Accurate Picture ◽  
The Matrix ◽  
Very High ◽  
Good Agreement

IntroductionThere have been several t.e.m. studies (1,2,3,4) of the dislocation arrangements in the matrix and around the particles in dispersion strengthened single crystals deformed in single slip. Good agreement has been obtained in general between the observed structures and the various theories for the flow stress and work hardening of this class of alloy. There has been though some difficulty in obtaining an accurate picture of these arrangements in the case when the obstacles are large (of the order of several 1000's Å). This is due to both the physical loss of dislocations from the thin foil in its preparation and to rearrangement of the structure on unloading and standing at room temperature under the influence of the very high localised stresses in the vicinity of the particles (2,3).This contribution presents part of a study of the Cu-Cr-SiO2 system where age hardening from the Cu-Cr and dispersion strengthening from Cu-Sio2 is combined.

The observation of defects on (100) CdTe surfaces by chemical etching

1992 ◽  
Vol 50 (2) ◽  
pp. 1424-1425
Author(s):  
M.E. Lee
Keyword(s):  
Single Crystal ◽  
Grain Boundaries ◽  
Single Crystals ◽  
Chemical Etching ◽  
Crystalline Perfection ◽  
Crystalline Defects ◽  
High Incidence ◽  
Crystallographic Defects ◽  
Cdznte Substrates ◽  
Device Technology

The crystalline perfection of bulk CdTe substrates plays an important role in their use in infrared device technology. The application of chemical etchants to determine crystal polarity or the density and distribution of crystallographic defects in (100) CdTe is not well understood. The lack of data on (100) CdTe surfaces is a result of the apparent difficulty in growing (100) CdTe single crystal substrates which is caused by a high incidence of twinning. Many etchants have been reported to predict polarity on one or both (111) CdTe planes but are considered to be unsuitable as defect etchants. An etchant reported recently has been considered to be a true defect etchant for CdTe, MCT and CdZnTe substrates. This etchant has been reported to reveal crystalline defects such as dislocations, grain boundaries and inclusions in (110) and (111) CdTe. In this study the effect of this new etchant on (100) CdTe surfaces is investigated.The single crystals used in this study were (100) CdTe as-cut slices (1mm thickness) from Bridgman-grown ingots.

Mounting an individual submicrometer sized single crystal

1996 ◽  
Vol 211 (6) ◽  
Author(s):  
R. B. Neder ◽  
M. Burghammer ◽  
Th. Grasl ◽  
H. Schulz
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Single Crystal ◽  
Single Crystals ◽  
High Vacuum ◽  
Nanometer Resolution ◽  
Micro Manipulator ◽  
Scanning Electron

AbstractWe developed a new micro manipulator for mounting individual sub-micrometer sized single crystals within a scanning electron microscope. The translations are realized via a commercially available piezomicroscope, adapted for high vacuum usage and realize nanometer resolution. With this novel instrument it is routinely possible to mount individual single crystals with sizes down to 0.1

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