Investigation of Surface Topography of Oxygen on Nickel Single Crystals by Helium Ion Backscattering

1972 ◽  
Vol 9 (2) ◽  
pp. 620-623 ◽  
Author(s):  
W. Heiland ◽  
E. Taglauer
CIRP Annals ◽  
2016 ◽  
Vol 65 (1) ◽  
pp. 541-544 ◽  
Author(s):  
Hideaki Takahashi ◽  
Hirofumi Suzuki ◽  
Yoshiharu Namba

Author(s):  
G. Lehmpfuhl ◽  
Y. Uchida

From the analysis of convergent-beam electron diffraction patterns it is well known that the intensity of some reflections may become most sensitive to the crystal thickness variation at special conditions for thickness and orientation. This can be understood as a dynamic effect as well as a kinematic effect of electron diffraction. Using such a diffracted beam for imaging, a small change in thickness of a single crystal can be observed in an electron microscope. At the beginning of the application of this technique only weak beams were used for imaging the surface topography of undistorted single crystals. Thickness differences down to the atomic level could be detected in darkfield micrographs of MgO and Au. However, the intensity of the weak beams was so low that long exposure times up to 2 minutes were necessary to record a micrograph at a magnification of 20,000. This magnification is the upper limit for the weak-beam darkfield technique for reasons of stability of the electron microscope. The thickness contrast can be explained already by the kinematical theory of electron diffraction.


1967 ◽  
Vol 45 (2) ◽  
pp. 453-479 ◽  
Author(s):  
J. W. Mitchell ◽  
J. C. Chevrier ◽  
B. J. Hockey ◽  
J. P. Monaghan Jr.

The mechanism of the deformation in tension of [321] axis square-sectioned single crystals of α-phase copper–aluminium alloys with [Formula: see text] and [Formula: see text] surfaces has been studied. Extensive use has been made of interference microscopy and carbon replicas for the determination of the surface topography of the bands of deformation. It has been shown that, in addition to the discrete slip lines which are seen with the optical microscope and in replicas, there is a background of plastic deformation on a much finer scale which is not resolved. The integrated step height across bands of deformation corresponding with this fine slip can be measured on the interferograms. The integrated step height between corresponding points on the opposite [Formula: see text] surfaces was found to be equal. The studies of surface topography were supplemented by work on the nature of the distributions of dislocations within the crystals by etching and transmission electron microscopy. It was found that the dislocations are largely present as interleaved pileups of parallel positive and parallel negative dislocations in near-edge orientations and as closely spaced multipolar distributions. Large pileups of several hundred dislocations have been observed and correlated with surface slip lines. They appear to be introduced as avalanches from surface sources. Characteristic features of this previously unrecognized type of band of deformation have been established and the mechanism proposed for the formation of the bands recalls many of the features of the dynamical model for the multiplication of dislocations discussed by Frank in 1947. The background on which the slip lines are superimposed appears to be due to the limited activation by the shear stress within the band of deformation of a uniform distribution of sources.


1983 ◽  
Vol 63 (2) ◽  
pp. 304-308 ◽  
Author(s):  
P. Chandrasekharam ◽  
D. Raja Reddy ◽  
B.K. Reddy

The oriented chemical growth of the oxides are studied on different surfaces of single crystals of zinc and cadmium and also of the sulphide of cadmium. The contact planes between substrate and oriented overgrowth were found by determining the facets upon which a particular orientation occurs. The orientation is found to depend on the type of facet, and hence on the surface topography of the substrate which could be determined in favourable cases. The clean surfaces of the metallic crystals used were prepared by electrolytic methods. The inner potentials of zinc and zinc oxide have been measured.


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