Kink and Crack Interfaces in Deformed 6H-SiC Single Crystals

1994 ◽  
Vol 357 ◽  
Author(s):  
X. J. Ning ◽  
P. Pirouz
Keyword(s):  
Low Temperature ◽  
Slip System ◽  
Single Crystal ◽  
Single Crystals ◽  
Basal Plane ◽  
Prism Plane ◽  
Secondary Slip ◽  
Micro Cracks ◽  
Indentation Tests ◽  
Temperature Deformations

AbstractWhen a 6H-SiC single crystal is deformed under indentation or uniaxial compression in orientations not favorable for the activation of the 1/3[1120](0001) easy glide system, the secondary slip system is activated. Additionally, for low- temperature deformations, “kinks” and/or micro-cracks form in the crystal. In this paper, experimental results on relatively lowtemperature compression and indentation tests of single crystal 6H-SiC, and the microstructure of the deformed crystals, are presented. Based on the results, the secondary slip system in 6HSiC has been determined to be 1/3[1120](1100), which may actually be a combination of alternate glide of 1/3[1120] dislocations on the (1102) and (1102) planes. Further, dislocation mechanisms for the nucleation of prism-plane and basal-plane cracks, and for the process of kinking, in deformed 6H-SiC are proposed.

scholarly journals The Stress Induced Martensite-Austenite Interface in Fe-15Ni-15Cr Single Crystals

1973 ◽  
Vol 31 ◽  
pp. 110-111
Author(s):  
G. A. Stone ◽  
G. Thomas
Keyword(s):  
Shear Stress ◽  
Slip System ◽  
Single Crystal ◽  
Single Crystals ◽  
Habit Plane ◽  
Maximum Shear Stress ◽  
Crystal Axis ◽  
Surface Study

A single crystal stressed in the [3]𝛄 direction at 185°K was transformed to 5% 𝛂 martensite and 2% Ɛ martensite by volume. The austenite slip system of maximum shear stress is the (11)𝛄 [01)𝛄. Fig. 1 shows a two surface study using the electron and optical microscopes. The a martensite is confined between £martensite plates with the (0001)Ɛ ∥ (11)𝛄. The size of the acicular martensite crystals is controlled by the spacing of the £ martensite plates. These £ martensite plates are seen in Fig. 1A as dark vertical bands. The axes of the acicular crystals lie in the (11)𝛄 plane. The £ martensite habit plane is defined as the plane perpendicular to the (11)𝛄 containing the vector defining the crystal axis.

Electromigration in Single Crystal Cadmium 1,*

1971 ◽  
Vol 26 (1) ◽  
pp. 18-20 ◽  
Author(s):  
W. B. Alexander
Keyword(s):  
Single Crystal ◽  
Single Crystals ◽  
Effective Charge ◽  
Basal Plane ◽  
Cadmium Vacancy ◽  
Significant Difference ◽  
Effective Charges

AbstractMeasurements of electromigration in single crystals of cadmium have been made as a function of orientation. The resulting values for the effective charge numbers are Z =1.54 ± 0.15 and Z⊥=3.20±0.3.The results are also expressed in terms of the effective charges for the separate atomic jumps, (1) to a vacancy in the same basal plane and (2) to a vacancy in an adjoining plane. While the parallelism of these findings with those for zinc is apparent, there is one significant difference. In cadmium vacancy creation (and annihilation) tends to alter the c-axis dimension preferentially.

scholarly journals Anisotropy of the Kinetic Friction on a Single Crystal of Ice

1978 ◽  
Vol 21 (85) ◽  
pp. 661-668 ◽  
Author(s):  
Katutosi Tusima
Keyword(s):  
Friction Coefficient ◽  
Slip System ◽  
Single Crystal ◽  
Tungsten Carbide ◽  
Basal Plane ◽  
Kinetic Friction ◽  
Track Width ◽  
Maximum Friction ◽  
Temperature Range

Abstract Measurements were made of the kinetic friction which occurs when a tungsten carbide ball slides in various directions on the surface of a single crystal of ice, the track width produced on the surface was also measured. Anisotropies were detected in both the friction coefficient and the track width. The track width φ was at a maximum when the ball was slid normal to the basal plane and a minimum when it was moving parallel to (0001) in the temperature range —5 to —30°C. Although the friction coefficient was at a minimum when slid normal to (0001) and maximum in parallel to (0001) at temperatures of —19°C and below, this relation was found to be reversed at temperatures of —10°C and above. Anisotropy in track width can be explained in terms of the amount by which a slip system contributes to deformation in a specimen. However, our understanding of frictional anisotropy calls for knowledge of the ploughing strength p defined by the adhesion theory of friction. It was found that p reached a maximum in parallel to (0001) and a minimum normal to (0001) and that the frictional anisotropy on (0001) was influenced by the value . A remarkable frictional anisotropy was also observed on the surface inclined to the basal plane at 30°; the maximum friction coefficient was twice the minimum, whereas the maximum track width was only 1.3 times the minimum.

Dislocation Boundaries and Slip Systems in Uniaxially Deformed Crystals

2001 ◽  
Vol 683 ◽  
Author(s):  
Grethe Winther ◽  
Xiaoxu Huang ◽  
Søren Fæster Nielsen ◽  
John Wert
Keyword(s):  
Single Crystal ◽  
Single Crystals ◽  
Crystal Orientation ◽  
Boundary Plane ◽  
Slip Systems ◽  
Crystal Boundary ◽  
Secondary Slip ◽  
Slip Planes ◽  
Planar Dislocation ◽  
Active Slip

ABSTRACTThe dislocations in the extended planar dislocation boundaries formed during deformation are generated by the active slip systems. Investigation of the boundaries is therefore a tool to obtain information on the active slip systems. Here, the orientation of the dislocation boundaries in uniaxially deformed aluminum poly- and single crystals are compared. It is found that the single crystal boundary planes are consistent with those found in polycrystals, indicating that the active slip systems in single and polycrystals are the same. However, boundaries are closer to the slip planes in the single crystals. This is taken as an indication that the secondary slip systems are more active in the polycrystal. The orientation of the boundary plane varies with the crystal orientation in a way that is consistent with activation of the five most stressed slip systems.

Plastic Behavior and Deformation Structure of Silicide Single Crystals with Transition Metals at High Temperatures

1993 ◽  
Vol 322 ◽  
Author(s):  
Y. Umakoshi ◽  
T. Nakashima ◽  
T. Nakano ◽  
E. Yanagisawa
Keyword(s):  
Brittle Fracture ◽  
Slip System ◽  
Single Crystals ◽  
Low Temperatures ◽  
Plastic Behavior ◽  
Deformation Structure ◽  
Secondary Slip ◽  
Ambient Temperatures ◽  
Brittle Transition ◽  
Increasing Temperature

AbstractThe mechanical and plastic behaviors of refractory silicide single crystals with Cllb (MoSi2), C40 (CrSi2, TaSi2 and NbSi2), D88 (Ti5Si3) and Cl (CoSi2 and (Co0.9Ni0.1)Si2) structures were investigated. The C40–type silicides were deformed by (0001)<1120> slip. Their yield stress decreased sharply with increasing temperature but NbSi2 and TaSi2 which were deformable even at low temperatures, exhibited anomalous strengthening around 1350°C. Deformation of Ti5Si3 whose ductile-brittle transition occurred around 1300°C was controlled by twins and the brittle fracture occurred on the basal plane. In CoSi2 the {001}<100> slip was only activated at ambient temperatures but addition of Ni activated {110}<110> slip as secondary slip system and improved the ductility. The creep behavior of MoSi2 and CrSi2 single crystals were also investigated and was found to be controlled by the viscous and glide motion of dislocations.

scholarly journals Further experiments on the behaviour of single crystals of zinc subjected to alternating torsional stresses

1930 ◽  
Vol 127 (805) ◽  
pp. 453-479 ◽  
Keyword(s):  
Single Crystal ◽  
Normal Stress ◽  
Single Crystals ◽  
Basal Plane ◽  
Present Experiment ◽  
Previous Experiment ◽  
Relative Orientation ◽  
Normal Stresses ◽  
Slip Direction ◽  
Twinning Plane

Object of Experiment .—From the results of a previous experiment on a single crystal of zinc, it was concluded that the formation of twins in zinc occurred on planes of the 101 ˉ 2 type and that the particular operative twinning plane (of the six available) was determined chiefly by the direction of slip on the original basal plane and possibly, to some extent, by the relative magnitudes of the normal stresses on the possible twinning planes. In this previous experiment the orientation of the crystal was such that slip on the original basal plane occurred in one direction only and one pair of complementary twins only was observed. From the results it was predicted that if a test were made on a crystal of suitable relative orientation of the crystallographic and straining axes such that all three slip directions became operative, then the operative twinning planes should change with the slip direction. The present experiment was planned in order to test this prediction. Again, in the previous experiment, of the two possible pairs of complementary twinning planes associated with any one slip direction, it appeared probable that the choice of the operative pair was influenced by considerations of normal stress on the twinning plane. The present experiment would, it was hoped, throw further light on this aspect of twinning.

Rolling Anisotropy of Ni3Al Single Crystals

1986 ◽  
Vol 81 ◽  
Author(s):  
Katsuya Watanabe ◽  
Masaaki Fukuchi
Keyword(s):  
Slip System ◽  
Single Crystal ◽  
Single Crystals ◽  
Tensile Strain ◽  
Compressive Strain ◽  
Rolling Direction ◽  
Sheet Plane ◽  
Active Slip System ◽  
Active Slip

AbstractThe rolling anisotropy of Ni3Al single crystals was studied. A single crystal sheet in the (011) plane showed remarkable anisotropy. Rolling the sheet in the [100] direction was simple but was almost impossible in the [011] direction. Substantial anisotropy was not observed in the (111) and (001) sheets. The texture of the rolled (011) and (111) sheets were {011}<011>. It is concluded that the rolling anisotropy of single crystal sheets is determined by the presence of active slip system related to compressive strain normal to the sheet plane, and tensile strain parallel to the rolling direction.

scholarly journals DC-Electrical Properties of TlGaTe2 Single Crystals under Hydrostatic Pressure

2011 ◽  
Vol 2011 ◽  
pp. 1-5
Author(s):  
Solmaz N. Mustafaeva ◽  
Shafag G. Gasymov ◽  
Elmira M. Kerimova ◽  
MirSalim M. Asadov
Keyword(s):  
Hydrostatic Pressure ◽  
Electrical Properties ◽  
Low Temperature ◽  
Single Crystal ◽  
Single Crystals ◽  
Considerable Increase ◽  
Localized States ◽  
Electrical Measurements ◽  
Effect Of Hydrostatic Pressure ◽  
Dc Electrical Properties

The effect of hydrostatic pressure (up to 0.82 GPa) on the electric properties of chain TlGaTe2 single crystals has been investigated in the temperature range 77–296 K. It has been shown that pressure leads to a considerable increase of conductivity (σ⊥) across the chains of TlGaTe2 single crystals. Parameters of localized states in the band gap of TlGaTe2 single crystal according to the low-temperature electrical measurements were obtained at various pressures.

THE EFFECTS OF GRAIN BOUNDARIES ON THE PLASTIC DEFORMATION OF ZINC CRYSTALS

1957 ◽  
Vol 35 (1) ◽  
pp. 38-47 ◽  
Author(s):  
G. B. Craig ◽  
B. Chalmers
Keyword(s):  
Plastic Deformation ◽  
Single Crystal ◽  
Grain Boundaries ◽  
Single Crystals ◽  
Basal Plane ◽  
Basal Slip ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diffraction Patterns

The tensile plastic deformation of single-crystal and tricrystal specimens of zinc was investigated by analysis of the external change in shape of the specimens, and of the changes in X-ray diffraction patterns. It was demonstrated that the single crystals deformed by slip on the basal plane, but pyramidal as well as basal slip occurred in specimens containing grain boundaries.

Single crystals of undoped Li2WO4 and Li2W1-0.0125Mo0.0125O4: Formation enthalpies, heat capacity in the temperature range 320-997 K

2021 ◽  
Author(s):  
Nata Ivanovna Matskevich ◽  
V.N. Shlegel ◽  
Anna Nikolaevna Semerikova ◽  
Dmitrii Andreevich Samoshkin ◽  
Veronika D. Grigoryeva ◽  
...  
Keyword(s):  
Heat Capacity ◽  
Low Temperature ◽  
Single Crystal ◽  
Single Crystals ◽  
Weight Control ◽  
Rare Events ◽  
Temperature Gradients ◽  
Czochralski Technique ◽  
Temperature Range ◽  
Formation Enthalpies

The Li2WO4 single crystal was first grown applying unique Czochralski technique with weight control and low-temperature-gradients. Single crystal of Li2WO4 is one of the perspective materials to search rare events....

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