Effect of aspect ratio on compression of MgO single crystals

1987 ◽  
Vol 6 (7) ◽  
pp. 862-864 ◽  
Author(s):  
K. C. Goretta ◽  
J. L. Routbort
Keyword(s):  
Aspect Ratio ◽  
Single Crystals

Directional Solidification of Refractory Intermetallics: Single Crystals and Composites

1993 ◽  
Vol 322 ◽  
Author(s):  
David P. Pope ◽  
Dilip M. Shah ◽  
William Romanow ◽  
Mark Huntley
Keyword(s):  
Aspect Ratio ◽  
Optical Imaging ◽  
Directional Solidification ◽  
Single Crystals ◽  
Intermetallic Compounds ◽  
Floating Zone ◽  
Growth Axis ◽  
Advantages And Disadvantages

AbstractDirectional solidification of intermetallic compounds using the optical imaging floating zone technique is discussed. The advantages and disadvantages of the technique are described, and the systems to which this technique has been applied are listed. Finally, application of the technique to growing in situ Cr2Nb/Nb composites is described. It is shown that well aligned, fine microstructures can be obtained using the technique. The aspect ratio of the Cr2Nb platelets is 200:1, or better, and are a few microns thick. The Cr2Nb has a strong <220> texture along the growth axis but the Nb is nearly random.

scholarly journals Critical sample aspect ratio and magnetic field dependence for antiskyrmion formation in Mn1.4PtSn single crystals

2021 ◽  
Vol 103 (18) ◽  
Author(s):  
B. E. Zuniga Cespedes ◽  
P. Vir ◽  
P. Milde ◽  
C. Felser ◽  
L. M. Eng
Keyword(s):  
Magnetic Field ◽  
Aspect Ratio ◽  
Single Crystals ◽  
Field Dependence ◽  
Magnetic Field Dependence

scholarly journals Confinement stabilises single crystal vaterite rods

2014 ◽  
Vol 50 (36) ◽  
pp. 4729-4732 ◽  
Author(s):  
Anna S. Schenk ◽  
Eduardo J. Albarracin ◽  
Yi-Yeoun Kim ◽  
Johannes Ihli ◽  
Fiona C. Meldrum
Keyword(s):  
Aspect Ratio ◽  
Single Crystal ◽  
Single Crystals ◽  
High Aspect Ratio ◽  
Cylindrical Pores ◽  
Track Etch

Single-crystals of vaterite, the least-stable anhydrous polymorph of CaCO3, are rare in biogenic and synthetic systems. We here describe the synthesis of high aspect ratio single crystal vaterite rods under additive-free conditions by precipitating CaCO3 within the cylindrical pores of track-etch membranes.

The Microstructure of Shock-Synthesized Diamond

1967 ◽  
Vol 25 ◽  
pp. 324-325
Author(s):  
Lucien F. Trueb
Keyword(s):  
Single Crystals ◽  
Preferred Orientation ◽  
High Magnification ◽  
Texture Pattern ◽  
Shock Process ◽  
New Type ◽  
Diffraction Diagram

A new type of synthetic industrial diamond formed by an explosive shock process has been recently developed by the Du Pont Company. This material consists of a mixture of two basically different forms, as shown in Figure 1: relatively flat and compact aggregates of acicular crystallites, and single crystals in the form of irregular polyhedra with straight edges.Figure 2 is a high magnification micrograph typical for the fibrous aggregates; it shows that they are composed of bundles of crystallites 0.05-0.3 μ long and 0.02 μ. wide. The selected area diffraction diagram (insert in Figure 2) consists of a weak polycrystalline ring pattern and a strong texture pattern with arc reflections. The latter results from crystals having preferred orientation, which shows that in a given particle most fibrils have a similar orientation.

A New Defect in Polyethylene Single Crystals

1973 ◽  
Vol 31 ◽  
pp. 70-71
Author(s):  
E. L. Thomas ◽  
S. L. Sass
Keyword(s):  
Single Crystals ◽  
Screw Dislocation ◽  
Small Distance ◽  
Dipole Model ◽  
Dislocation Dipole ◽  
Chain Folding ◽  
Black And White ◽  
Polymer Crystal ◽  
Different Types

In polyethylene single crystals pairs of black and white lines spaced 700-3,000Å apart, parallel to the [100] and [010] directions, have been identified as microsector boundaries. A microsector is formed when the plane of chain folding changes over a small distance within a polymer crystal. In order for the different types of folds to accommodate at the boundary between the 2 fold domains, a staggering along the chain direction and a rotation of the chains in the plane of the boundary occurs. The black-white contrast from a microsector boundary can be explained in terms of these chain rotations. We demonstrate that microsectors can terminate within the crystal and interpret the observed terminal strain contrast in terms of a screw dislocation dipole model.

Preferential Sputtering of Ni3Al Single Crystals Studied Using Atom-Probe Field-Ion Microscopy and XPS

1981 ◽  
Vol 39 ◽  
pp. 16-17
Author(s):  
M.P. Thomas ◽  
A.R. Waugh ◽  
M.J. Southon ◽  
Brian Ralph
Keyword(s):  
Single Crystals ◽  
Photoelectron Spectroscopy ◽  
Surface Composition ◽  
Depth Profiling ◽  
Analytical Techniques ◽  
Atom Probe ◽  
Probe Field ◽  
Preferential Sputtering ◽  
Argon Ion Bombardment ◽  
Argon Ion

It is well known that ion-induced sputtering from numerous multicomponent targets results in marked changes in surface composition (1). Preferential removal of one component results in surface enrichment in the less easily removed species. In this investigation, a time-of-flight atom-probe field-ion microscope A.P. together with X-ray photoelectron spectroscopy XPS have been used to monitor alterations in surface composition of Ni3Al single crystals under argon ion bombardment. The A.P. has been chosen for this investigation because of its ability using field evaporation to depth profile through a sputtered surface without the need for further ion sputtering. Incident ion energy and ion dose have been selected to reflect conditions widely used in surface analytical techniques for cleaning and depth-profiling of samples, typically 3keV and 1018 - 1020 ion m-2.

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.

Bright field and weak-beam images of dislocations gliding on (001) planes in F.C.C. metals

1978 ◽  
Vol 36 (1) ◽  
pp. 352-353
Author(s):  
H. P. Karnthaler ◽  
A. Korner
Keyword(s):  
Single Crystals ◽  
Dislocation Structure ◽  
Room Temperature ◽  
Stage Ii ◽  
Bright Field ◽  
Weak Beam ◽  
Standard Orientation

In f.c.c. metals slip is observed to occur generally on {111} planes. Glide dislocations on intersecting {111} planes can react with each other and form Lomer-Cottrell locks which lie along a <110> direction and are sessile since they are split on two {111} planes. Cottrell already pointed out that these dislocations could glide on {001} planes if they were not split. The first study of this phenomenon has been published recently. It is the purpose of this paper to report some interesting new details of the dislocations gliding on {001} planes in pure Ni, Cu, and Ag deformed at room temperature.Single crystals are grown with standard orientation and strained into stage II. The crystals are sliced parallel to the (001) planes. The dislocation structure is studied by TEM and the Burgers vectors ḇ and glide planes of the dislocations are determined unambiguously.In Fig.l primary P and secondary S dislocations react and form composite dislocations K.

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