Papers by Keyword: Cube Texture

Abstract: Textures and related anisotropy effects which occur in certain industrial processes are presented for as-cast, deformed and annealed (recrystallized) Aluminium alloys and products. They are analyzed in detail and discussed based on their formation mechanisms, which are growth selection during solidification and the formation of new grains during casting and recrystallization, glide on selected slip planes during plastic deformation and oriented nucleation and oriented growth of new grains during recrystallization. Alloy composition and constitution that control microstructure evolution during processing (e.g. casting, extrusion, hot and cold rolling, annealing) determine the material quality and product performance.In these cases industrial processing of Aluminium alloys is specifically designed to control textures to achieve superior anisotropic properties and so better meet special product requirements. Examples are given for resulting properties, like strength and formability / anisotropy effects in packaging and automotive sheet applications. Other examples are given for the etching behaviour of high purity Aluminium capacitor foil and strength anisotropy of age hardened extrusions for aerospace applications.

Abstract: Texture, structure, and magnetic and mechanical properties of thin tape substrates fabricated of ternary nickel alloys with chromium, tungsten, molybdenum, and vanadium have been investigated. It has been shown that in Ni_93.8Cr_4.0Mo_2.2, Ni_88.5Cr_6.2V_5.3 and Ni_88.4Cr_9.2W2.4 alloys a sharp cube texture can form, which is stable up to high annealing temperatures. In the Ni_87.6Cr_8.0Mo_4.4 alloy, other weak orientations are present, along with the strong cube component. The possibility of obtaining a sharp cube texture after primary recrystallization is controlled by the quantitative relationship between the texture components in a cold-rolled tape, which is determined by the method of orientation-distribution functions. Three alloys studied are non-magnetic at 77 K.

Abstract: A series of oxygen free high conductivity copper samples with different initial grain sizes, cold rolling conditions and storage times as well as slightly different impurity contents was used to investigate the effects of these initial parameters on the development of cube texture during recrystallization. For rolling reductions of 90% and 95%, cube textures with volume fractions between 3% and 50% were observed. Higher rolling reduction led to a stronger cube texture. Cube texture development is very sensitive to the initial grain size before rolling. In general, fine grained material gives a strong cube texture after recrystallization, and the requirement on fineness of the grain size may vary for materials with different purity. Large sample widening during rolling can largely inhibit the development of cube texture after recrystallization. Neither storage time, nor the slight change in impurity content had large effects in the present investigation.

Abstract: The migration rates of C->Si, Si->C, and Si->Sj were assumed to be high and those of Si->Si and all other rates to be low. Here Si(i=1,2,3,4) is a variant of S orientation and C->Si means the growth of a cube grain into an Si grain. The textural development through grain coarsening was simulated as a function of the ratio of the high rate to the low one. The compromising effect surely promotes the development of the cube texture but its decisive development requires any asymmetry between C->Si and Si->C migration processes.

Abstract: The cube texture in rolled and annealed fcc metals and alloys has long fascinated metallurgists because of its high symmetry and extreme sharpness. This paper demonstrates and analyses the texture perfection that is developed in a copper sample. Reasons that have been advanced to explain the development of the texture during recrystallisation and grain growth are discussed. Orientation selectivity is favoured during growth but more particularly in the nucleation stage. Especial attention is paid to the rapid recovery which cube oriented crystals undergo on heating after plane strain deformation and which is the basis for its uniquely preferential nucleation. Various metallurgical factors are known to affect the strength of the cube texture in practice and explanations for some of these are presented.

Abstract: The goal of the present study inspired by previous works on high purity aluminiun was to manufacture aluminium sheets of commercial purity, grade 1050, with a strong cube texture. In this preliminary work on AA1050, sheets which cube volume fraction reaches 65% have been manufactured. Parameters controlling cube orientation development are mainly the solute dragging due to impurities in solid solution and the stored deformation energy. Besides the 85% cold rolling (CR), two extra annealings and a slight cold rolling are introduced in the processing route to increase the cube volume fraction. The cube orientation, whose substructure is equiaxed, is important for its recovery. It develops thanks to the difference of stored energy relative to that of its first neighbors; the slight cold rolling enhances growth of these cube grains.

Abstract: Grain boundary mobility in preferential growth of cube grains ({100}<001>) was evaluated by in-situ electron back scattering diffraction pattern (EBSP) analysis in order to clarify the fundamental mechanism of primary recrystallization in pure aluminum foils of 99.9% purity thermo-mechanically processed in the industrial production route for aluminum foils for electrolytic capacitors. We have carried out the continuous EBSP measurements during recrystallization of the aluminum foils heated to various temperatures in the chamber of scanning electron microscopy (SEM). We have succeeded in dynamic observation of the preferential growth of cube grains by the in-situ EBSP analysis. The in-situ EBSP analysis could reveal the migration rate of grain boundaries surrounding the cube grains. It was clarified that the proportional relation between migration rate and annealing time was satisfied. The stored energy providing the driving force for the grain boundary migration during primary recrystallization could be estimated from the misorientation within the deformed grains. The mobility of the grain boundary could be evaluated using the measured grain boundary migration rate and stored energy. Then the activation energy could be estimated by the in-situ EBSP analysis at various temperatures ranging from 270°C to 310°C. The obtained activation energy was 124 kJ/mol, which approximately corresponded to that for the diffusion of impurity such as iron or silicon in aluminum. This suggested that the rate-determining process of the grain boundary migration of cube grains was impurity diffusion in the pure aluminum foils.

Abstract: Copper foils cold rolled up to 92% reduction exhibited a low intensity of the β-fiber texture and a high intensity of the cube and RD (rolling direction)-rotated cube components. After annealing, the recrystallization texture of the foils could be characterized by the mixture of the cube and the S components. An initial strong cube texture with a large grain size might remain a less developed rolling texture component, cube or RD-rotated cube, which would be the source of the S component in the recrystallization texture.