Influence Of Crystal Orientation Research Articles

The influence of crystal orientation on the high temperature fatigue crack growth of a Ni-based single crystal superalloy

Compact-type (CT) fatigue crack growth (FCG) specimens have been prepared from single crystals of SRR99. The macroscopic crack planes {hkl} and propagation directions 〈UVW〉 were (110)[1̄10], (110)[1̄11], (110)[001], (111)[11̄0] and (001)[010]. FCG tests were conducted at 650 and 850°C in air at 10 and 1 Hz at an R ratio of 0.1. At 650°C, (110) and (111) specimens showed a frequency-dependent FCG rate, not apparent for (001)[010], due to increased cuboidal cross-slip and reduced reversibility at lower frequency. Slip homogenization at 850°C prevented this effect. (001)[010] demonstrated a lower Paris regime FCG rate at 850°C than at 650°C due to crack bifurcation at the higher temperature. Conversely, a higher FCG rate occurred for (110) and (111) specimens at 850°C, as crack tortuosity decreased as it changed from propagation along the γγ′ interface at 650°C to precipitate cutting at 850°C. An orientation-dependent FCG rate and fracture path was found. At 650°C orientations able to accommodate crack tip shear on primary slip planes near-parallel with the crack front provided the best FCG resistance. At 850°C the best FCG response was found for the same orientations that now developed large scale ridges as a result of out-of-plane cuboidal slip.

SPR-based sensors studied by electron energy loss spectroscopy and attenuated total reflection

Electron energy loss spectroscopy (EELS) and attenuated total reflection (ATR) are employed to excite and study the surface plasmon of thin silver films. The films studied are used in surface plasmon resonance- (SPR-) based sensors, where the surface plasmon is excited using the evanescent wave from a light beam totally internally reflected from the base of a prism (Kretschmann configuration) and the resonance is observed as an attenuation of the reflected light intensity as the angle of incidence of the light in the prism is scanned. Such sensors exploit the high sensitivity of the surface plasmon frequency to the refractive index of layers of adsorbed molecules on the surface. The surface plasmon frequency, however, is also a sensitive function of the silver film preparation conditions which control the preferred crystallographic orientation and surface roughness of the silver. Surface roughness is known to strongly affect the surface plasmon frequency and there is much controversy concerning the influence of crystal orientation on the dispersion characteristics of the surface plasmon. The present work investigates the effect of varying the deposition temperature of the films on the surface plasmon characteristics (measured by EELS and ATR). The results are discussed in terms of the crystallographic orientation (studied by X-ray diffraction (XRD)) and the surface roughness (studied by scanning tunneling microscopy (STM)) of the films.

Study of Ultraprecision Orthogonal Microdiamond Cutting of Single-Crystal Copper

The results of experimental study of ultraprecision orthogonal microdiamond cutting of single-crystal copper are presented. The orthogonal cutting tests were carried out on an ultraprecision fly-cutting machine at various nominal depths of cut from 3.0μm down to 0.01μm (10nm). The machinability in microcutting and the influence of crystal orientation on the microcutting process are discussed from the standpoints of chip formation, cutting force and surface integrity. It is confirmed that continuous chips are formed under all cutting conditions examined. The magnitude of the cutting force and the shear angle are substantially influenced by the crystal orientation at depths of cut of 1μm or more, while they are not notably influenced with depths of cut below 1μm.

The shape of the crystal/melt interface during the growth of lithium niobate crystals by the Czochralski technique

Abstract The influence of crystal orientation, melt height, and crystal rotation rate on the shape of the crystal/melt interface for LiNbO3 was investigated. While the crystal orientation and the melt height has little influence on the interface shape, the shape was found to be strongly affected by the crystal rotation rate. Above a critical rate, inversion from a convex to a concave interface occurs. The critical rate is inversely proportional to the crystal diameter. A comparison between critical rotation rates for LiNbO3 calculated by relations predicting such rates and those obtained by growth experiments is given.

Study on Ultraprecision Orthogonal Microdiamond Cutting of Copper Single Crystal.

The results of experimental study on ultraprecision orthogonal microdiamond cutting of single-crystal copper are presented. The orthogonal cutting tests were carried out on an ultraprecision fly-cutting machine under various nominal depths of cut from 3.0 μm down to 0.01 μm (10 nm ). The machinability in microcutting and the influences of crystal orientation on the microcutting process are discussed from the standpoints of chip formation, cutting forces and surface integrity. It is confirmed that the continuous chips are formed under the whole cutting conditions examined. The magnitude of the cutting force and the shear angle are substantially influenced by the crystal orientation at depths of cut of 1 μm or more, while they are not notably influenced with a decrease in the depth of cut below 1 μm.

The influence of crystal orientation on the fatigue softening behaviour of severely predeformed copper: Schrank, J., Prantl, W. and Stuwe, H.P. Mater. Sci. Eng. A Mar. 1989, 110, (1–2), 61–68

The influence of crystal orientation on the fatigue softening behaviour of severely predeformed copper: Schrank, J., Prantl, W. and Stuwe, H.P. Mater. Sci. Eng. A Mar. 1989, 110, (1–2), 61–68

The influence of crystal orientation on the fatigue softening behaviour of severely predeformed copper

Softening experiments were performed with cold-rolled single crystals with initial orientations near 〈001〉, 〈111〉 and 〈123〉 and a drawn polycrystal. The change in microstructure and flow stress decrease caused by cyclic deformation (ϵp = ±1 × 10−2; N = 50) is investigated. The dislocation rearrangement after 50 cycles is pronounced. The substructure and its change are different for different cystal orientations, both in single crystals and in the polycrystal. Nevertheless the softening curves indicate that the details of the cell wall structure are of minor importance for softening. There is no simple correlation between the cell size change and the flow stress decrease. Softening should therefore be caused mainly by dislocation annihilation.

Influence of crystal orientation on open circuit voltage and first diode factor at SIS solar cells

Influence of crystal orientation on open circuit voltage and first diode factor at SIS solar cells

On the influence of crystal orientation on the high resolution image contrast of polytypes

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Optical frequency mixing in planar waveguides: Influence of crystal orientation

Optical frequency mixing through nonlinear mode coupling in a planar waveguide, fabricated with a cubic or uniaxial dielectric, is discussed. A threewave interaction is examined and the optimum crystal orientations that lead to the highest efficiency are determined in those particular cases in which they do not depend on the field distribution of the modes. The analysis is carried out in detail for cubic crystals; sensitivity to misalignments is also studied and numerical results are reported.

The influence of crystal orientation on the electron energy loss spectrum of monocrystalline silver films

In electron energy loss measurements (50 keV) on monocrystalline silver films in transmission the intensity of the 3.8 eV volume plasma loss is found to be dependent on the crystal orientation. If the crystal is tilted relatively to the electron beam by an angle α the elastic intensity I el in the primary direction oscillates by 10%, the intensity of the volume plasmon however varies much stronger similar to I el ; it can become even zero at certain angles α. The intensity of the surface loss is nearly proportional to the elastic intensity. An explanation of this phenomenon is missing. Presumably it must lie in the dynamic theory of electron diffraction.

Influence of crystal orientation in the structure of electrodeposited copper

An X-ray diffraction study was made of copper electrodeposited on low index planes of copper single crystals. Three characteristic stages occur during the process: (a) epitaxial growth, (b) twin development, (c) polycrystalline growth.The deposit thickness, Δh, attained just before polycrystalline growth starts, is hyperbolically related to the cd, high cds giving thinner deposits. For a given cd, Δh is a function of the crystallographic orientation of the base single crystal in the order ▪ It is suggested that this behaviour is directly related to the atomic density and to the stability, as measured by work function, of the different crystallographic planes.The mechanism of polycrystalline growth is also discussed.

Influence of Crystal Orientation and Oxide Structure on the Interface States of GeGeO2

AbstractHexagonal, tetragonal, and amorphous oxides were prepared on 111‐, 110‐, and 100‐surfaces of germanium. Interface‐states were determined by the ac‐field effect. The hexagonal oxide shows on the 111‐surface, the tetragonal on the 100‐surface the lowest density of surface states. Amorphous oxide does not show significant differences for the three orientations. This shows clearly, that the matching of the lattices at the interface is of importance for the existence of surface states.

On the influence of crystal orientation on solution-grown GaAs laser diodes

Solution-grown GaAs p-n junctions were formed simultaneously using three differently oriented wafers, namely, the

The emission of fast secondary atoms from ionically bombarded copper “reflections”

Abstract A study was made of the production of fast secondary atoms from copper poly-crystalline and single-crystalline targets. The “reflected” atoms were measured with a secondary emission detector. The targets were bombarded with Ar + ions, mainly at an energy of 15 keV. We found, by application of pulsed ion beam techniques that the energy distribution of the measured atoms has a sharp maximum at the mean value expected for single elastic biparticle collisions. The total yield of these “reflections” was measured as a function of the angle of incidence of the ion beam. It increases much faster than the sputtering ratio and reaches a value of more than 1% of the primary ion beam for very oblique incidence. Experiments on a single crystal show the influence of crystal orientation on the “reflections”. The influence of crystal order is much smaller than the analogous one for sputtering. This shows that the process of sputtering of neutral copper atoms takes place deeper inside the crystal than the emission of fast particles. Most “reflected” atoms were found at a “reflection angle” of 70° with the normal, independent of the angle of incidence of the primary iom. The maximum “reflection” angle will be determined by the surface roughness, which is not strongly dependent on the angle of incidence for polycrystalline targets. An estimate of secondary sputtering due to the “reflections” and the surface roughness gives a yield in the order of 10% of primary sputtering.

Influence of Crystal Orientation on the Surface Behavior of InSb

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