Showing papers on "Texture (crystalline) published in 1969"

The significance of texture parameters in phase analysis by X‐ray diffraction

Abstract: The theory of the direct comparison X-ray method of phase analysis is extended to correct for preferred orientation effects. Texture parameters are defined to assess the type and intensity of preferred orientation using data from diffractometer patterns. The analysis is illustrated with results obtained on three austenitic stainless steels.

Orientation distribution, elastic and plastic anisotropy in stabilized steel sheet

Abstract: The texture of commercially produced stabilized steel in the temper rolled condition has been represented by a three-dimensional orientation distribution, defined by a set of coefficients of a series of generalized spherical harmonics. The coefficients have been used to calculate the elastic and plastic properties in the plane of the sheet and comparison is made between the predicted and experimental values. Errors in the experimental determination of pole figures have been analysed and estimated.

Direct evidence for distinctive, stress-induced nucleus crystals in the crystallization of oriented polymer melts

Abstract: A previous paper proposed a model for polymer crystallization under stress [1]. This paper suggested that there could be distinctive crystals which formed under stress at unusually high temperatures to act later as nuclei for the bulk of the crystals. The present paper details definitive evidence for these nucleating crystals. Electron microscope observations are fully consistent with the expected two-phase structure for crystallization under stress, although they are not conclusive. However, X-ray diffraction patterns recorded while the samples crystallized under stress, at the appropriate elevated temperature, conclusively demonstrated the two-stage nature of the crystallization. First, a small number of crystals (type I) form which are highly c-axis oriented, followed by a second group of crystals (type II) having a more complex stress dependence of texture patterns. This is in complete agreement with the model [1] that c-axis-oriented fibers induce transversely growing lamellar crystals. Type...

Stress and Design in Bivalved Mollusc Shell

Abstract: An animal's shell is subjected to stress throughout its life, and residual stress can be released and measured as strain. The shape and texture of the shell are advantageous features of design.

A Study on the Orientation Effects in Polyethylene in the Light of Crystalline Texture Part 4 Truly Single Texture on Unidirectional Rolling

Abstract: As a continuation of previous works aimed at obtaining macroscopic specimens of polyethylene with a simple texture, samples were prepared by unidirectional rolling (without previous drawing) followed by heat-relaxation. This resulted in a macroscopic lamination consisting of two transparent outer zones and a turbid zone in the interior. It was confirmed by full pole figure analysis, both at wide angles involving three reflections and at low angles, that the two transparent edge zones were truly single-textured as regards both the subcell and the superperiod, the orientation at the two edges being in mirror relation. The middle zone corresponded partly to a superposition of the structure at the two edges, but contained also additional complicating features. The new findings support several of the basic assumptions made in the previous papers of the series based on less complete evidence. Further, they provide the best characterised and most uniquely defined textures known in a polycrystalline polymer so far, in a form suitable for further macroscopic examination. Also the present findings should be relevant to the interpretation of the crystal morphology of oriented polymers in general and to the understanding of the rolling process in particular.

Registered embossed high pressure laminates

Abstract: A PROCESS FOR THE PRODUCTION OF DECORATIVE TEXTURED AND SCULPTURED LAMINATS HAVING A FIRST COLOR AND SCULPTURED EFFECT IN ONE AREA IN REGISTRY WITH THE REMAINDER OF THE LAMINATE WHICH HAS ANOTHER COLOR AND A DIFFERENT TEXTURE. D R A W I N G

Production of patented steel wire

Abstract: A method for producing patented steel wire by depositing the wire in nonconcentric overlapping turns on a moving conveyor belt and controlling its temperature to convert its texture to ferrite and pearlite.

Influence of the substrate and electrolyte on the composition and properties of thin electrodeposited Ni-Fe films

Abstract: The characteristics of electrolytes will be described which prevent composition gradients from developing as the result of differences in Ni++ and Fe++ diffusion, during the electrolytic formation of Ni-Fe films. This is accomplished by using an electrolyte additive which results in a solution which can be operated at a Ni-Fe ratio that is the same as desired in the film, making both the Ni++ and Fe++ deposition diffusion controlled. Using a specific electrolyte with these characteristics, the influence of the substrate on the film composition, structure, and resultant properties has been demonstrated by changing the composition gradients induced by electrolyte diffusion effects. The metallurgical structure (grain size, porosity, crystal texture, composition) and the magnetic properties ( H_{c}, H_{k}, \alpha_{q} , magnetostriction) of films deposited on Au and Cu were examined. Using the Au substrate, films were made at constant deposition conditions from 100 to 4000 A thick. The average Fe content of the films changed from 28 to 18 percent over this thickness range. Films deposited under the same conditions onto Cu substrates had a lower average Fe content; e.g.,13 percent at 600 A thick. Film compositions as a function of thickness are described by the sum of two exponential terms; one term takes into account electrolyte diffusion effects on composition and the other term takes into account the electrode effect on composition. Previously reported data are analyzed in the same manner and composition gradients as a function of film thickness are confirmed to be larger than in the work reported here. Low values of coercive force and dispersion were obtained only from films thicker than about 300 A deposited on Au. These low coercive forces and dispersion are shown to be due to the isotropic crystal structure, fine grain size, and relatively mild composition fluctuations in the Ni-Fe promoted by the characteristics of the Au substrate in the electrolyte. On Cu the films were magnetically isotropic and high in H c below thicknesses of about 4000 A, due to the highly porous film structure and large grain size induced by the Cu substrate. The deposition potentials, monitored during the formation of the film, reflected the composition of the alloy depositing and provides a technique for choosing the optimum substrate and electrolyte.

The Structure, Texture and Growth of Bronze Electrodeposits on Polycrystalline Substrates

Abstract: SummaryA study of the electrodeposition of Cn-Sn bronzes from a cyanide-stannate bath under potentiostatic conditions at 65°C has been made. It has been shown that the results are in agreement with those obtained previously under galvanostatic conditions. The growth and textures of the deposited alloys were also investigated. Continuation of the structures of cube-textured copper cathodes was most pronounced at intermediate overpotentials i e 500–650 mV. Under these conditions the initial base-oriented growth gave way to fibrous structures with increasing deposit thickness. At low overpotentials (300 mV) metallographic evidence indicated considerable lateral growth in the deposits and the texture was found to be [111] whereas at high overpotentials (700–800 mV) growth was mainly outward and the texture was [110]. These results are in agreement with theoretical predictions concerning ‘free-growth’ textures and suggest that little adsorption takes place under these conditions. At intermediate potentials the...

Chemical Structure and Properties of Heat Treated Coal in the Early State of Carbonization (XXI)

Abstract: The changes of reflectance and anisotripic structure of heat-treated coals have been examined.The reflectance of H.T. coals in creases with the rise of heating temperature, and the increasing rate of reflectance is abruptly great above the resolidification temperature .Howerer, the accurate measurements of the reflectance are difficult above the resolidification temperature due to the development of anisotropic texture.The anisotropic texture appeared in the H. T. coals is assorted as follows; isotropic texture, fine and coarse mosaic texture, incompletely and completely fibrous texture, and leaflet texture.On the basis of this assortment, the degree of development of anisotropic regions has been estimated quantitatively with point-counter methods.1) The variation of anisotropic texture depends on the rank of coal.For non caking and weakly caking coals, it is difficult to find the anisotropic texture in the heat treated coal and the isotropic texture keeps even at the higher temperature.In case of caking coals, the mosaic texture appears by heating, and the same texture hold up to the higher temperature .For coking coals, the isotropic texture turns to masaic and fibrous textures. Then the latter increases with the rise of heating temperature.2) The temperature at which anisotropic textue appears.The anisotropic texture becomes obervable for caking and coking coals kept for 4 hours at constants temperature in the range 390-400°C.3) The effect of residence timeFor coking coal heated at 400°C, the anisotropic region expands gradually with residence time.And the region of fibrous texture increases with the icrease of residence time.

Pressure Sintering of Gallium Arsenide

Abstract: Pressure sintering of gallium arsenide was studied in vacuum at 900° to 1000 °C and 9000 to 43,200 psi. The optical transmission of nearly theoretically dense gallium arsenide was about one-fourth less than that of equally thick single crystals. Density-time curves indicated that at least two densification mechanisms occur and apparently overlap. Microscopic observations indicated that plastic flow was one of the mechanisms. Plastic flow was further evidenced by the crystallographic texture of the grains, as determined by X-ray diffractometry. The rapid initial plastic flow densification stage is not adequately described by the McClelland densification rate equation. Diffusional secondary densification mechanisms may be operative at higher densities.

Magnetostrictive Effects in Cylindrical Films

Abstract: The classical expression of the magnetoelastic energy of a monocrystal is transformed according to the most general rotation of the crystalline axes with respect to a given reference system. It is then possible to calculate the effect of a given stress on a polycrystalline material. It is shown that it is only for perfectly random crystallographic orientations that it is possible to cancel the ``macroscopic'' magnetostrictive effects of all the strains at the same composition for a magnetic alloy. If a cylindrical magnetic film with a preferential texture is made insensitive to an axial elongation, it will exhibit a magnetostrictive skew of its magnetic easy axis when the wire is twisted. The microscopic effects of stresses are also investigated in all cases: the so‐called ``isotropic stresses'' give a dispersion of the easy axis.

Fibrous structure and texture of extruded rods of alloy Ak8

Abstract: 1. Extruded rods of aluminum alloys have a complex fibrous structure that is generally independent of the shape of the cross section of the piece. 2. A completely axial texture is found only near the axis of extruded rods. With increasing distance from the axis the axial texture diminishes and the and texture is retained. The rolling texture (110) [112] predominates in the area of the future rim of large crystals. 3. The axial texture component <100< forms a compact region whose shape varies with the distance from the axis of the rod and matches the type of deformation in the given section. 4. The variation of the texture through the section is determined by the difference in the type of deformation in the different sections of the rod. With elongation in the lengthwise direction there occurs: a) symmetrical narrowing of the cross section in the center; b) unsymmetrical narrowing of the cross section in the intermediate zone; c) narrowing in the radial direction and slight elongation in the tangential direction in the outer zone of the future rim.